The Unknown of the Order (Harry Potter: Hogwarts Mystery

The Cave

Tulip had to admit to herself, as she stumbled on a rocky surface, that Jacob must be quite a powerful wizard if he could successfully transport that many people so far without any of them splinching. This did little to please her, as she trusted him less than Argus Filch trusted her. 

"Pleasant spot," she mumbled, as she glanced over the rocky cliff to the waves many feet below. 

"This way," said Jacob, and he climbed over the edge of the cliff, carefully working his way down to the sea. 

One by one, the others followed. Jacob jumped from a large boulder into the sea. The others glanced at each other, before Sarah shrugged and jumped in after him. They swam across the icy water, nearly choking at the strong smell of the salt, through a small gap in another rock that made a large, dark cave. 

The only sound was the water dripping from their sopping wet clothes as Jacob led the way with the tip of his wand alight. 

"Here we go," he said, stopping at a blank part of the cave wall. Tulip felt her spine tingle. The air around here was so thick with dark magic that she could sense its presence. 

They waited as Jacob examined every inch of the wall. 

"A blood curse," he said, at last. "Simple enough."

"Unless you're Spellman," said Merula. 

"That was no ordinary blood curse," spat Sarah. "I could handle this one easily."

Jacob was smiling. "Then by all means, do." He gestured for Sarah to step forward. 

She did, striding up to the wall and examining it carefully, muttering incantations under her breath. Then, she performed a slicing charm on the palm of her hand. Blood pooled in her palm, and she rubbed her hand along the wall, leaving a trail of blood, like a demented rainbow, on the cave wall. 

Sarah healed her cut as the silver outline of an arch appeared on the wall, and the bloodstained rock under the arch vanished. 

Tulip sighed. She'd grown so accustomed to how easily Gryffindors could be manipulated into stupid things, such as volunteering to maim themselves just to prove a point, that she now found it rather dull. She'd rather have seen Jacob's blood splattered on the wall, or Elena's. 

Sarah stepped through the archway with her shoulders hunched, as though she suspected any moment to be drowning in blood once more. When nothing happened, she relaxed and the others joined her on the other side. 

They were on the shore of some kind of underground lake. In the distance, Tulip could make out a tiny island, an eerie, green light emanating from it. It was clear that was where they were meant to go next. 

"Spread out," said Jacob, "see what you can find."

Though they had no idea what they were looking for, they all lit their wands and began searching the area. Tulip's spine shuddered as she focused on the Dark Magic, trying to tap into the source and determine where it came from. They seemed to be surrounded by it. 

"Don't touch the water," she announced to the others. She wasn't sure why, but she was suddenly certain that to touch the water would be to meet death. 

After what seemed hours, Jacob finally called, "I got it."

Tulip saw that he had somehow got hold of a chain that stuck out of the water. He pulled on it and a small, black boat appeared from beneath the surface. It was perfectly dry. 

"Only room for one," said Jacob. 

"What? No way. We could fit two," said Sarah. 

"I don't mean room for one body," said Jacob. "I think this boat is enchanted. Only one wizard at a time."

"Well, you're mad if you think we're letting you go," said Tulip. 

"I'm the only one who has even an inkling of what we're dealing with," said Jacob, his teeth clenched. 

"I'll go," said Sarah. "I've experienced enough dark magic to know what to look for."

"No way," said Diego and Barnaby together. 

"I'll do it," said Merula, "none of the rest of you are smart enough--"

"It's got to be me," said Jacob. Tulip could tell he was resisting the urge to shout. "We've got to move quickly. Look, if I was going to betray you all, do you think I'd have brought you this far?"

When none of them gave a reply, he climbed into the tiny boat and it set off on its own, across the water. 

They waited, staring after Jacob as the boat led him to the island. It was far enough away that Tulip couldn't see what he was doing, but he stayed there for an impossibly long time. Still, no one spoke. They remained motionless, staring ahead at the small, dark figure on the island for what could have been an hour. Finally, he got back into the boat and made his way to their shore. He was a little over halfway back across the water when it happened. 

Skeletal hands erupted from the surface of the water, clinging to the boat and preventing it from continuing. 

Elena gasped. Tulip looked down to see several skeletons climbing from the surface up to their bank. She pulled out her wand. She'd had enough experience to know how to deal with inferi. Her wand raised, she blasted them with fire. Sarah, Talbott, Diego, and Barnaby all shot flames at the water too, but there must have been hundreds of inferi climbing toward them, bent on tearing them apart. 

Merula and Elena stepped forward,  green lights glowing from their hands. 

"Leave!" she heard Merula hiss at the inferi, in a hoarse, ghostly voice unlike any Tulip had ever heard. "Return to your watery grave."

Tulip realized with a jolt that the girls were attempting to control the inferi. It worked a little; a few of the inferi stopped, looking around in confusion, and the hoard slowed slightly. It was enough so that the combined firepower of the others was able to keep them from stepping out of the water. 

The boat hit the bank and Jacob leapt from it. His eyes glowed green as he ordered the monster back as well. The hoard paused and Jacob's eyes became steely and blue again. 

"Run," he told them. "That won't hold them off for long."

They all retreated, away from the green lake and the army of standing skeletons, back down the cave passage. They dove back into the water and swam the hundred yards to the cliff, climbing as fast as they could. At the top, they finally collapsed and attempted to regain their breaths. 

Tulip coughed and spluttered. She'd nearly drowned in her panicked scramble through the water; Barnaby had had to go back for her and pull her up to the surface as she spit out a mouthful of seawater. 

"We need to get out of here," said Jacob urgently, once he'd recovered enough to speak. "Voldemort probably knows we were here."

"Where's the horcrux?" asked Talbott. 

"Gone."

"What do you mean, gone?"

"I mean, it wasn't there. Somebody else got here and took it before we did."

"Accio horcrux," said Sarah at once, pointing her wand at Jacob. Nothing happened.

"I'm not lying!" Jacob hissed. 

"This happened before," explained Barnaby, as he helped Tulip to her feet. He was a strong swimmer, and the mad dash through the choppy water hadn't effected him as much as the others. "Someone had already taken the last horcrux we went to find."

"Who?" asked Sarah. 

"I don't know, but I'd love to discuss it with you all somewhere safe," said Jacob. 

"You were controlling the inferi!" she told him. 

"Yes, and if I hadn't, you'd all be dead. Now hurry up, all of you, unless you want to be left behind."

They scrambled to link together. Tulip had only just managed to grab Talbott's arm when Jacob spun on the spot and disapparated.