The first room contained a giant chessboard.
The squares were blue and white and each one was at least two metres square. The chess pieces standing on them were black and white. They were not quite as big as the statues in the Chess Garden at home, but they were still taller than Captain Zachary. The walls of the room were crumbling. The holes in them showed the bare concrete, electrical wiring and plastic pipes hidden inside. More plants were growing in the gaps and water was dripping down from the ceiling. Hundreds of broken multi-coloured fragments from what must have been murals were scattered all over the floor and the chessboard. Two more repair robots fitted with long whirring floor brushes were sweeping the fragments off the board as they walked in.
"Here we are then, Stephen's grandchildren," said Chata, appearing on several wall screens around the room. "Welcome to your first challenge."
"Thank you, Chata. We're very happy to be here," said Alice.
"Yes. Great," said Ellen. "What do we have to do?"
"I thought we'd start with something simple," said Chata. "Out of fairness, we should both have a chance to look at each other's capabilities first. I imagine the chess-playing computers you've grown up with are a lot more advanced than I am. So we'll begin with a basic game. I've linked the lock on the doors to the next room..."
Alex looked across the room and saw the doors on the far side of the chessboard in the opposite wall.
"...to the chessboard," said Chata. "If you can achieve checkmate, the doors will unlock and you can continue."
"What happens if you checkmate us... ma'am?" said Captain Zachary.
"The same thing in reverse," said Chata. "If I win, the door you came in through unlocks and you can go back to the start and leave with no hard feelings."
"Hold on. We need the notebook." said Ellen.
"Yes. So you all keep telling me," said Chata. "But fair is fair. If you want it, you need to win."
"She's right," said Alice. "If we can't win a simple game, we don't deserve to get it."
"That's the spirit, Princess," said Chata. "And remember, Lord Blackstar and your weird friends from Sirius are in the same boat. If they lose, they're out as well. So, are you willing to play?"
"Yes," said Alex.
He was surprised again at how sure he sounded. He had never played chess like this before, not for such high stakes and not when one mistake could mean it was all over. But, as Ellen and Alice had pointed out, they were Stephen Tarquin's grandchildren. They had all been playing chess since they were old enough to understand the rules. Alex was not a grandmaster, but he was not bad either and Alice was even better. They could do this.
"Good," said Chata. "Then let's begin. As you're my guests, take white. The pieces are automatic. Just say the move you want to make out loud."
"OK," said Alex.
Nothing happened. Alex looked across at Alice, waiting for her to start. She, Ellen and Captain Zachary were all looking at him, and Alex realised he had just volunteered.
"Oh. Right. OK."
He stepped forward to the edge of the board. The giant chess pieces seemed to tower over him. It felt like standing at the edge of a forest and looking in. This was going to be a lot less convenient than looking down at a chessboard from above. He was going to have to be careful to keep track of what was going on in the parts of the board he could not see properly. Alex breathed in, hoped to the seven sisters that he was not going to make a mistake and ruin this, and started.
"Pawn to King 4," he said, using the ancient, descriptive chess notation that Chata was bound to have in her memory banks.
There was a soft whispering sound as the giant pawn glided forwards two squares – to the fourth square in front of Alex's king – and stopped.
"Pawn to Queen's Bishop 3," said Chata.
"Pawn to Queen 4," said Alex.
"Pawn to Queen's Knight 3."
The large black and white pieces moved neatly on both sides of the board. Alex relaxed a bit. The board was bigger than any he had played on before, but chess was still chess and he knew how to play it. They went through several more moves each.
"Queen to Queen's Bishop 2," said Chata. "This is wonderful. I've forgotten how much I enjoy this. Thank you again, Prince Alex."
"You're welcome. Rook to Queen's Bishop 1," said Alex.
"Yes. Great. Come on, Alex," said Ellen. "Hurry up."
"Your highness, don't distract him," said Captain Zachary.
"I'm fine," said Alex, without looking around, keeping track of where all his pieces were. But as he said that, he realised Ellen was right. He was playing carefully. Lord Blackstar and the Sirians were playing Chata – or other versions of her – in the other rooms right now. For all he knew, one or both of them might have won already and be in their second rooms. This was not just a game. It was also a race. If they wanted the notebook, he needed to win quickly.
"Knight to King's Bishop 5," he said.
"Pawn to Queen's Bishop 4," said Chata.
"Pawn to Queen's Bishop 4. Pawn captures Pawn," said Alex.
A green transmitter laser glowed underneath Chata's pawn. It disappeared from its square and rematerialised at the side of the board. Alex's pawn slid onto the square.
"Well done, your highness," said Captain Zachary.
"Yes. Great. Do it again," said Ellen.
Alex nodded, studying the board and reminding himself not to get overconfident. He just needed to checkmate Chata as fast as possible.
"Bishop to King's Rook 5," he said.
"Knight to King's Bishop 4," said Chata.
"Bishop to King's Bishop 4. Bishop captures Knight," said Alex. He would do this the simple way; capture enough of Chata's pieces to create an opening and then checkmate her king.
"Yes! Keep going," said Ellen. On the screen, Chata clicked her teeth.
"Pawn to Queen's Rook 7," she said.
"Rook to Queen's Rook 2. Rook captures knight," said Alex.
"Drat!" said Chata, shaking her head. "Four hundred years is too long. I really am out of practice."
Alex had to agree. Chata was playing reactively, trying to get close to his moves with the nearest pieces she had. She was not stopping to think if her pieces could do anything useful when they got there. She was almost walking into some of his captures.
"Pawn to King 5."
"Queen to King 4. Queen captures Pawn," said Alex.
"She isn't very good at this, is she?" murmured Alice.
"I know. This is our lucky day," whispered Ellen.
"Yes, but she's a computer," said Alice. "Her memory should be perfect..."
"I can hear you, your highnesses," said Chata. Her face on one of the screens turned to look at them. The others kept frowning at the chessboard from different angles. "As I've already told you, it's been four hundred years. And six hundred with no maintenance team or anywhere to order spare parts from. A lot of my systems, both software and hardware, are unfortunately not what they used to..."
Something exploded behind them with a loud bang. Alex spun around from the chessboard, where he had just been about to capture another of Chata's pawns. A jagged piece of plastic flew past his head. Captain Zachary whipped around, grabbing his laser pistol. One of the pipes in one of the exposed sections of the wall had just burst open. Thick, acid-smelling green gas began streaming into the room.
"Oh, great Shiva!" said Chata, suddenly looking terrified. "That's the emergency decontamination system! It's overloaded. Don't inhale! Don't inhale!"
Alex pulled up the front of his tunic and clamped it over his mouth. Ellen and Alice used their hands and Captain Zachary used his elbow as the gas, which was heavier than air and stayed close to the floor, started to billow across the room.
"I'll let you out!" said Chata. "Forget the game! Just run!"
Alex spun back around as Alice and Ellen rushed straight past him. He and Captain Zachary ran after them across the chessboard, weaving between the pieces, towards the other doors. As they reached them, the door lock whirred, groaned and then threw out electrical sparks.
"Oh, no!" said Chata.
"What's wrong?" shouted Ellen, from behind her hand.
"That's broken too! I can't disconnect it from the board!" said Chata, her eyes wide with terror.
"Let us out the other way, ma'am!" yelled Captain Zachary, spinning around towards the doors they had come in through. The lock there groaned and sparked too.
"No! That's jammed as well!" said Chata. "Wait... Yes! The link to the board is still connected. It's working. Quick! Finish the game. Achieve checkmate! That will open it!"
"Are you crazy?!" shouted Ellen.
"Do it! Hurry up! It's your only chance!" called Chata, as the two repair robots shot across the floor and tried to block the leaking pipe with their floor brushes. Alex could see straight away that they were not going to be able to do it. "You've got about four minutes!"
"Oh, Seven Sisters!"
Alex looked at the chessboard again. The gas was moving slowly, but it was already wrapping around the furthest white pieces. "Uh... Bishop to King 7!"
"Queen to Queen's Rook 4," said Chata.
"Pawn to Queen's Knight 4! Pawn captures pawn!"
"Rook to King's Knight 2."
"Come on, Alex!" said Ellen.
"I'm trying!" said Alex. He thought he had almost had Chata in check twice already, but she had just slipped out of it, even with how badly she was playing. He was used to chess computers automatically recognising and announcing checkmate. Alex froze as a horrible thought occurred. What if Chata's chess programming was damaged too? Could she even recognise checkmate anymore?
"Wait!" said Alice, grabbing his arm. "Knight to King's Knight 2."
"What?" said Alex, looking at her. That took one of his furthest pieces backwards instead of forwards.
"Pawn to King's Knight 1. Pawn captures Knight," said Chata.
Behind them, the lock on the doors to the next room sparked again. But this time, there was a more positive sounding whirr, as if it was trying to open.
"Yes!" said Alice. "Bishop to Queen's Bishop 3."
"Rook to Queen's Bishop 3," said Chata.
"What?" said Alex, again. "What are you...? What?"
"We're playing Losing Chess!" said Alice. "It's a variant game. I read about it in The Four-Limbed Game last night. We don't have to win. We have to lose."
"Correct! Sorry I didn't tell you!" said Chata.
"Why the halon not?!" shouted Ellen.
"This is meant to be a challenge! I didn't want to make it too easy!" said Chata. "I did give you a clue!"
"When?" said Ellen. "And I meant why didn't you tell us this when..."
"Pawn to Queen's Knight 2," said Alice, moving more of their pieces back across the board as the gas reached the middle.
"Rook to King's Knight 8. Princess Alice, you can't win – lose – simply by running!" said Chata, as her pieces followed them, moving into the spaces Alice was creating in the middle of the board. "You need to let me take your pieces."
"No, we don't!" called Alice. "Checkmate!"
Chata blinked. Alex stared at the board. Alice had not put Chata in check. The black king was safe. Their white king was surrounded on all sides with nowhere to move to, but... Alex blinked himself. The black pieces were blocking all the places the white king could move to. They were in checkmate. Alex's eyes widened as he realised Alice had just played chess backwards, by giving Chata obvious moves to make. But when Chata had made them, she had put the white king in check.
Behind them, the door lock to the next room sparked and then pinged. The doors started to slide open. They all ran back towards them as the tendrils of gas crept forwards.
"She did give us a clue," said Alice. "She said we needed to achieve checkmate. Not that we needed to checkmate her. This is Losing Chess. We needed to checkmate ourselves."
"Actually, you could have just lost all your pieces. That would have been fine too," said Chata. "But yes! Go! Hurry!"
"You still could have mentioned it earlier!" shouted Ellen as they ran through the doors into the second room.
* * * * * * *
At the same time, Lord Blackstar, Darla and Will walked through the middle doors into their first room.
"This is going to be one really interesting story to tell everyone when we get home," said Darla. "Assuming, of course, you can actually win, Uncle Damon..."
"Be quiet, Darla," said Lord Blackstar. "And you are not to tell anyone anything about this. Certainly not what I've been... Never mind. All right, computer. Let's get on with this."
"Certainly, Lord Blackstar," said Chata, as she appeared on the room's wall screens. "I'm glad to see you're so keen."
"Of course I am. This is more important to the future of the Pleiades than you're aware of," said Lord Blackstar. "It is absolutely essential that I get to that notebook before... Never mind. But I thought you said this was going to be challenging."
Will and Darla looked at the room. It contained another giant chessboard with black and green squares. Giant black and white chess pieces were standing on it. But instead of a full chess set, the board was set only with queens, four in each colour, arranged in the middle of the board.
"Oh, it is," said Chata. "You're the only grandmaster here, after all. It's only fair I give something little bit harder to start with than I'm giving everyone else."
"What, the Eight Queens Puzzle?" said Lord Blackstar, gesturing at the board. "This is supposed to be difficult?"
"The what?" said Darla.
"I'm sorry, my lady. I've never heard of it either," said Will.
"That's because you don't read enough chess history," said Lord Blackstar. "The Eight Queens Puzzle is a chess problem from 1848. The goal is to arrange eight queens on the board so that none of them can capture any of the others. Though I'm not sure how it's supposed to be hard. This was ancient before you were invented, computer."
"Actually, my earliest direct ancestor was designed in 1832," said Chata. "But don't worry, Lord Blackstar. This is harder than it looks."
"I don't see how," said Lord Blackstar, "considering that it was solved centuries ago. There are ninety-two different solutions to it. This is number seven."
"Oh, you know all of them?" said Chata. "Good. That should let you save some time. Because your challenge, Lord Blackstar, is to find a new one."
Lord Blackstar's eyes narrowed.
"There aren't any new ones," he said.
"If you want the notebook, you going to have to prove yourself wrong," said Chata. "Like this. Queen 1 to Queen's Bishop 3."
One of the black queens slid diagonally forwards one square. Will and Lord Blackstar studied the board. The piece had moved, but it had kept to the rules of the puzzle. It still could not capture, or be captured by, any of the white queens.
"Your task, Lord Blackstar," said Chata, "is to get all four of your queens to the other side of the board. If one of them can be captured – even once – it's all over."
"What?" said Will, his eyes going wide. "But, my lady, how on Magenta – on Earth – are we supposed to... Oh, dear."
"Over to you, Uncle Damon," said Darla.
"Are you serious?" said Lord Blackstar, looking up at Chata.
"Completely," said Chata, smiling. "I told you this would be..."
"That's not what I meant," said Lord Blackstar. "This is your idea of a challenge?"
There was a long pause.
"Yes, it is, Lord Blackstar." said Chata, glaring at him. "It's nice to hear you're so confident, so let's hope you don't have to..."
The whole room suddenly shook. Vibrations ran across it in several directions at once. The pieces rocked on the chessboard as the floor almost jumped up and down. Will and Darla staggered to keep their balance.
"Oh, great Kali! Look out!" cried Chata, as several chunks of the ceiling fell in. Will, Darla and Lord Blackstar all moved as they smashed down on the floor and the chessboard, sending pieces flying in every direction.
"Ah," said Darla, as the shaking stopped. "So this is the room that's going to fall down at any moment."
"Drat. I was afraid of this," said Chata, peering up at the ceiling from her screens. "This room was originally built to recreate the famous game played by Nikito and Evangelinski during the Great San Francisco Earthquake of 2217. But it wasn't designed to last four hundred years. The earthquake simulator is connected to the board and I can't switch it off. It's going to start tremors at random moments."
"Is that safe?" said Will.
"No, it most definitely isn't," said Chata, peering at the ceiling again. "You're going to have to find a new solution fast, Lord Blackstar. If we have to play for longer than five minutes, it could bring the whole roof down on top of...
"Don't worry," said Lord Blackstar. "This is going to take considerably less than five minutes. Queen 1 to Queen's Rook 1."
The first white queen moved, not forwards, but backwards, towards their side of the board.
"Queen 3 to King's Rook 4," said Chata. Another black queen moved to a different, but still safe square.
"Queen 2 to Queen's Knight 1," said Lord Blackstar.
The second white queen moved all the way back, to the first row of squares on their side of the board, as the floor shook again. Darla grabbed Will's forearm to keep her balance as more pieces of the ceiling fell in.
"Queen 3 to Queen's Knight 5," said Chata. Another of the white queens moved into the middle of the board.
"Queen 3 to King 1," said Lord Blackstar, shifting his feet and keeping his balance as another tremor ran through the room.
"Queen 2 to Queen's Knight 3," said Chata, as another chunk of the ceiling fell. Will and Darla stepped apart as it smashed on the floor between them.
"Queen 4 to King's Knight 1," said Lord Blackstar, examining his fingernails and not even looking at the chess board as the last black queen slid all the way back to the first row on their side.
"Lord Blackstar, were you even listening to me?" said Chata. "I said you need to get all your queens to my side of the board. Not yours."
"Yes, I was," said Lord Blackstar. "But we are playing a chess game, aren't we, computer?"
"...Yes," said Chata.
"Then you also need to get all of your queens to my side of the board without having any of them captured," said Lord Blackstar. "How exactly are you going to do that now?"
Chata blinked. Darla and Will looked at the board. All the white queens were lined up along the first row on their side of the board on alternate squares. None of them were standing on the same columns as any of Chata's queens, which meant that all the columns her queens were on had a white queen on both sides of their final square. If Chata was going to keep her queens out of danger, she could not move into any of them.
"Oh! Well done, sir," said Will. "Very clever."
"Yes," said Darla. "Who'd have thought that spending ten years planning the perfect checkmate would actually be useful for something else?"
"For the last time, it was not the entire ten year... Never mind," said Lord Blackstar. "You have still got a chance, computer. You could sacrifice one of your queens to capture one of mine and make a bigger opening..."
"No, I can't. That doesn't help," said Chata. "I have to get all my queens to your side. Not just some of them..."
"Yes, I know," said Lord Blackstar. "And there's no way you can do that now. So are you going to try anyway and lose, or are you going to admit that I've won – you can't move without getting captured, so this is basically the same thing as checkmate – and open the doors?"
The floor trembled again as Chata as she ground her teeth.
"Very well," she said. On the other side of the room, the next set of doors slid open.
"Thank you. If you really wanted to make this challenging, number seven was a bad choice to start with," said Lord Blackstar, as they walked across the chessboard. "You'd have been much better off with number twenty two. But even then, I don't know why you though this was going to be difficult. A five year old could have worked it out."
"I guess this is Shahbanu Mat rather than Shah Mat, sir," said Will. ""The Queens are dead.""
"Yes. And four of them in one go," said Darla. "After this, getting rid of Jessamine should be a piece of cake."
"Do not say that outloud!" said Lord Blackstar,as he stalked through the doors into the second room.