In the Amazon, Dr. Rick Spartan, his wife, Marion, and manservant, Chachinga are walking through a jungle. He then sees a temple.
Dr. Spartan: Marion! Cachinga! We found it the ancient burial heap of Sklar Gringat. I told you legend plenty true, Cachinga.
Chachinga: Yes. Amazing.
They run towards the temple as Marion trips and breaks her ankle.
Marion: My ankle! I think it's broken.
Dr. Spartan: Cachinga, make plenty fast for camp. Fetch medicine kit for wifey, bring here quicky, quicky. 'K, 'k?
Cachinga runs off.
Marion: I'm sorry, honey. I know you're excited. Go on. I'll be fine here Alone.
Dr. Spartan: Ok.
He runs off.
Marion: Huh?
Dr. Spartan: Love ya!
He goes up the steps and moves a sphere with his spear and the sphere rolls down towards Marion. She rolls out of the way as Dr. Spartan descends and sees a chest. He reads the inscriptions.
Dr. Spartan: "Take not my head or a curse on you. My body shall forever avenge the wrong you do. " A curse. This day just gets better and better.
He opens it and grabs a shrunken head, and it speaks.
???: You were warned!
He drops the head as a hand touches his shoulder and sees a headless creature, with a face on its chest, stands there and he screams.
Fred was driving the Mystery Machine as fast as he could passing traffic trying to get to school.
Daphne: Slow down, Fred.
Fred: I can't. I don't want to be late for school.
Shaggy: Like, since when don't you want to be late for school?
Fred: Since I found out who our new biology teacher is.
All: Who?
Fred: Dr. Rick Spartan.
Scooby: Never heard of him.
Fred: That's because you don't read trap magazines like I do. The guy's a legend.
Y/N: Let me guess, he builds traps?
Fred: No. He just gets out of them a lot.
He swerves and Velma and Shaggy go to the side of the van.
Shaggy: Sorry.
Velma: No, it's ok. You don't need to move.
Shaggy: Really? Well, does that mean, like, you want to, uh, maybe, like, be friends again?
Velma: Maybe.
Daphne and Y/N see this and smile.
Shaggy: Well, uh, maybe me, too.
Fred swerves and Scooby comes over to the two.
Scooby: Maybe me three.
They reach school as Dr. Spartan recounts his battle with the headless horror to the class.
Dr. Spartan: The headless horror had me pinned against the wall. He punched me again and again and again. And picked me up by the throat and threw me to the ground and stomped on me over and over and over. Both my arms were broken. I had 16 fractured ribs.
Fred: What did you do?
Dr. Spartan: Do? The only thing I could do. I kicked it right in the face. It stumbled back, giving me just enough time to climb up the rope using only my left pinky.
Fred: No way!
Dr. Spartan: But that's the way it goes when you live the life of adventure. Right, Cachinga?
Cachinga: If you say so.
Dr. Spartan: Now listen up. I don't know much about biology, so if you want to know what a spleen is, you go read a book. But if you want to know how to escape the clutches of an 800-pound sumo wrestler who's trying to put a poison dart in your back, then you're in the right place. Class dismissed.
Student: But there's 45 minutes left.
Dr. Spartan: Cachinga!
Cachinga throws his spear at the clock breaking it.
Dr. Spartan: I said class dismissed!
The class runs out as Fred goes up to Dr. Spartan.
Fred: Dr. Spartan, wow! I'm your biggest fan. I've read about all your adventures. And, you know, we have a lot of adventures, too.
Dr. Spartan: You don't say.
Fred: Yeah. We solve mysteries. We've almost been killed a couple of times. Don't you just love it when that happens? Isn't it just the best?
Fred: Absolutely!
Gang (Except Fred): Not really.
Fred: So, do you still have that shrunken head? I sure do. It's super creepy, too. Hey, you want to see it? Absolutely!
Gang (Except Fred): Not really.
Dr. Spartan: Why don't you all come by the house for dinner tonight and I'll show you my whole collection of cool stuff.
Fred: Oh, that would be awesome!
Dr. Spartan: And make sure to bring your appetites. We're eating cow.
Gang: Ew!
Cachinga: He means steak.
Gang: Oh!
At Spartan's home everyone was eating.
Scooby: This is yummy!
Marion: Thank you. It is such a joy to be able to go to the supermarket and get cow right off the shelves. It's so much easier than chasing it down.
Scooby and Shaggy stop eating.
Scooby and Shaggy: Huh?
They then eat again.
Daphne: So, how long will you be teaching at the high school, Dr. Spartan?
Dr. Spartan: Long enough for Marion to have a little break. Living in the jungle's kind of rough on her.
Marion: It's the little things you miss. Warm showers, dishwasher, not having to check your back every morning for ticks.
She grabs the plates.
Dr. Spartan: You rest up, honey. A few months of r and r and we'll be ready to hit the adventure highway again. Right, Cachinga?
Cachinga: Quite.
Y/N: So, how long have you worked with Dr. Spartan?
Cachinga: Quite a while, actually. We were students at Oxford, and upon graduation, he hired me straight away to be his assistant.
Shaggy: What kind of name is Cachinga?
Cachinga: I have absolutely no idea. My real name is Charles. Charles Wheetlesby. Rick calls me Cachinga because he likes to pretend, I'm a wild savage. The pay's good, so I don't mind.
Dr. Spartan: Then why don't you wear the outfit I bought you?
Cachinga: I'm not putting on a bearskin and antlers.
Dr. Spartan: That's what savages wear.
Cachinga: I've got the spear. Isn't that good enough?
Dr. Spartan: No! You just look like a dude with a spear.
Cachinga: Well, I'm sorry if I'm a disappointment. If you will excuse me, I'll be in my yurt.
Cachinga walks away as Marion comes in.
Marion: You shouldn't be so hard on him, Rick. He saved your life more than once.
Dr. Spartan: Yeah, I know. I'll go apologize. But first, what do you say we go see that shrunken head?
They go to Dr. Spartan's room and see all the stuff he has collected, and they look around.
Scooby: All of this from your adventures?
Dr. Spartan: Yep. Well, all except that clown mask. I bought that in Reno. Here it is the shrunken head of Sklar Gringat.
They see the head.
Dr. Spartan: Do you want to hold it?
Fred: Absolutely!
Gang (Except Fred): Not really.
Daphne: You're not worried about the curse?
Dr. Spartan: Nah. I left that headless thing thousands of Miles away in the Amazon jungle. There's no way it-
They all feel a rumble with a roar. The doors close and the ceiling breaks and they see the headless monster. It shrieks at them. Dr. Spartan tries to open the door to no use.
Dr. Spartan: It won't open!
He tries to fight the monster, but the monster grabs him and throws him and grabs him by the leg. Fred grabs a spear and hits the monster on the body.
Fred: Y/N, Shaggy, Scooby, the spears!
Shaggy, Scooby, and Y/N grab the spears and force the monster back as Dr. Spartan joins them.
Headless Monster: I shall return! I shall be with you forever!
It retreats. Soon after Marion treats Dr. Spartan's wounds.
Dr. Spartan: I don't understand how that thing could have found me here. Is everything all right?
Cachinga: I heard a frightful commotion.
Dr. Spartan: Where you were? Why you not come when monster make bad-bad?
Y/N: Dr. Spartan, what can you tell us about the curse?
Dr. Spartan: It was carved into the box. It said if I took the head, its body would avenge the wrong I did forever.
Scooby: That's a long time.
Dr. Spartan: I can't spend the rest of my life running from that thing. I've got to find a way to break the curse.
Shaggy: But how are you gonna do that?
Dr. Spartan: I have no idea.
Velma: But I know someone who might.
Velma and Shaggy went to Velma's mom and told her what was happening.
Angie: Hmm. A shrunken head curse. That's a lot of bad mojo. Not easy to break.
Velma: Then there's nothing we can do? I didn't say that. I just said it wouldn't be easy. I'll go get my curse book.
She walks away.
Velma: I'm glad you came with me, shaggy.
Shaggy: I'm way glad you asked.
Shaggy: To be honest with you, Velma, like, I really missed you Uh, uh, us.
Velma: Me, too.
They were about to hold hands when Angie came back and dropped a huge book on the table.
Angie: Good news! I think I found an incantation to break the curse. Let's see, now. Ok. It says the incantation has to be said in a jungle.
Velma: The jungle? But the Amazon's thousands of Miles away.
Angie: It doesn't have to be the Amazon. Any jungle will do.
Shaggy: But, like, dudes, we don't have a jungle in Crystal Cove.
Velma: Hmm. Wait! Yes, we do. The botanical gardens. They've got that new mini rainforest. That's a jungle.
Angie: It also says the incantation has to be recited by a jackal.
Velma: Great. Where are we going to get a talking jackal?
Angie: I could order you one, but it'll take a couple of weeks.
Shaggy: Hey, wait a minute. What about Scooby-doo? Like, he can talk.
Velma: It's worth a shot.
Night came and the gang along with Dr. Spartan went to the botanical gardens.
Dr. Spartan: What are we waiting for? Let's do this.
Velma: The instructions say we can't start until precisely midnight.
Fred checks the clock.
Fred: Forty seconds to go.
Y/N: Where's Cachinga at?
Dr. Spartan: Ah, he's cheesed off about the way I talked to him last night. He says I don't respect him. Says I take him for granted. Natives.
Angie: Yoo-hoo!
They see Angie come out with a stick.
Angie: Mind if I join in? I just love incantations. They're such a hoot. Oh, I brought you this.
She hands Scooby the stick.
Scooby: Do I need this for the ceremony?
Angie: Not really. It just adds a little sizzle.
Fred: Midnight. Ok, scoob, you're up.
Scooby digs a hole and starts chanting.
Scooby: Wama, wama, yoy, yoy. Yoy, yoy, hippy, pippy.
He then grabs the shrunken head and puts it in the hole.
Scooby: Shrinky head, go back to jungle.
He then covers the hole with dirt as the others chant.
Gang: Nyup! Nyup!
Scooby: I did it!
Shaggy: Good job, scoob.
A rumble is felt, and the headless creature comes out from the dirt and shrieks.
Shaggy: On second thought, Zoinks!
Angie: Maybe you needed a jackal after all.
Dr. Spartan: Why won't you leave me alone?!
Headless Monster: You have plundered not just my tomb, but countless others. I shall follow you all the days of your life!
Dr. Spartan attacks the creature, but the creature grabs him and throws him into a tree.
Headless Monster: You shall never be rid of me!
The creature laughs and escapes as the gang takes Dr. Spartan to the hospital.
Nurse: He'll be fine. He just needs rest and quite a few operations.
Cachinga comes running in.
Cachinga: Oh, dear me! Rick, what happened?
Dr. Spartan: Like you give a whoop. What are you talking about?
Cachinga: Of course, I do.
Dr. Spartan: Ah, who cares? It doesn't matter. Just go back to Oxford, Charles. I don't need you anymore. I'm quitting.
Fred gasps as Marion hugs him.
Marion: Oh, darling! Are you sure?
Dr. Spartan: I'm sure. Maybe, just maybe that thing will leave me alone if I stop all this adventure stuff.
Marion: Yes. Yes, maybe it will.
Fred: But, Dr. Spartan, you can't quit. You're awesome. The world needs guys like you.
Dr. Spartan: I'm sorry, Fred, the gig is up. It's time to start living the life of an average boring Joe.
Scooby: I thought his name was Rick.
Fred: Dr. Spartan, please, don't quit. Give us one more chance to figure out how to stop that thing.
Dr. Spartan nods as the gang returns to the garden and looks around for clues. They then see a huge contact lens.
Daphne: What is it?
Fred: I'm not sure.
Y/N: It looks like huge contact lens.
Velma: Jinkies! That's right. Just before the creature threw Dr. Spartan against the tree, he hit it right in the eye. It must have fallen off.
Fred pulls out a miniature video camera from the contact lens.
Fred: Hey, look at this. It's a miniature video camera.
Shaggy and Scooby go towards them.
Shaggy: Like, that's not all. Scooby and I found this where the creature came out of the ground.
They saw a ring. Velma takes it and inspects it.
Velma: Oxford.
They all look at each other. Back at the hospital the gang comes back with Sheriff Stone and the other sheriff's as Cachinga waits outside Dr. Spartan's door.
Fred: There he is sheriff! Arrest that native.
The sheriff's approach Cachinga and arrested him.
Cachinga: Arrest me? What on earth for?
Sheriff Stone: These kids, uh, they say that you're that headless thing that's been whompin' on Dr. Spartan. I tend to agree. Take him away.
They take Cachinga away.
Cachinga: No! There's been some mistake. This is ridiculous. I'm British. Stop groping me, you rapscallion.
Sheriff Stone turns to the gang.
Sheriff Stone: Good job. For once I think you got it right.
Y/N points at him.
Y/N: Did you just compliment us?
Sheriff Stone: Repeat that to anyone and I will deny it.
He walks away as the gang enters Dr. Spartan's room.
Dr. Spartan: What's going on out there?
Fred: It was Cachinga. He was pretending to be the headless horror all along.
Dr. Spartan: I never trusted that guy. Wait! That means the curse is fake. There's no creature. Ha, ha! I can go back to the jungle, live the life of adventure again. It's gonna be all right!
Fred and Dr. Spartan high five when another rumble is felt, and the wall breaks open and the headless monster comes out.
Headless Monster: I don't think so!
It shrieks.
Fred: Let's get him out of here.
They all run out of the room with Dr. Spartan on the bed as the Headless monster chases them.
Fred: Velma, Daphne, get on!
They jump on the hospital bed as Velma uses an IV stand to make a sharp turn and the headless monster throws a counter at the group but misses as the chase continues. The monster continues to throw stuff.
Shaggy: Yikes! We're never gonna make it!
Scooby grabs a fire extinguisher and sprays it at the monster as they exit the building. The monster runs outside as Fred activates his trap and it is caught in a net.
Fred: Gotcha!
Scooby: It worked.
The police arrived once again.
Sheriff Stone: What in the name of kettle corn is going on? I thought you said he was the creature.
Daphne: Sorry we had to trick you, sheriff, but we needed everyone to believe it was Cachinga so we could set a trap for the person who's really behind this.
Fred took off the costume and it was Marion.
Dr. Spartan: Marion!
Sheriff Stone: But how did you know that she'd attack- I don't get that!
Fred: We knew that if Dr. Spartan found out that the curse was fake, he'd want to go back to living a life of adventure in the jungle.
Velma: A life she definitely didn't want.
Marion: Fine. I admit it.
Y/N: Well, you kind of have to. We caught you in the costume.
Sheriff Stone: But how did you know it was her?
Fred: We found this ring at the botanical gardens. A woman's ring. You went to Oxford, too, didn't you?
Marion: Yes.
Dr. Spartan: But, Marion, why did you do it?
Marion: Because I love you! Because I hate living in the jungle. It's icky. I decided if I couldn't convince you to give up that life, I'd scare you out of it. I came up with the fake legend of Sklar gringat. I forged an ancient map to the ruins and put it someplace you'd find it. I knew you wouldn't be able to resist the challenge. You would be so consumed with finding your next great treasure, you wouldn't be thinking of me, as usual. I pretended to break my ankle because I knew you'd send Cachinga for help and go up into the ruins by yourself. And when you did, my plan fell into place. It gave me a chance to sneak around the back of the ruins, which were actually an old abandoned movie set. The headless horror costume was the final piece of the puzzle. I had it specially designed and took months of pilates to train my abdominal muscles to the point where I could control the mouth with my abs.
Dr. Spartan: But the shrunken head it talked to me.
Marion: I got it at a Halloween store. You can record whatever you want it to say. I'm sorry, darling. I never meant to hurt you. I just wanted us to live a normal life. Which we could have if it weren't for those meddling sycophants. Can you ever forgive me?
Dr. Spartan: Sure, I do, baby. I know I'm not the easiest guy to live with. You were just trying to get through to me. Don't worry, we'll work it out. Sheriff, I don't want to press any charges.
Sheriff Stone: Yeah, I, uh, figured.
Dr. Spartan: Take me back to my room?
Marion: Anything.
Dr. Spartan: Cachinga, come.
Cachinga: Thank you. It's been lovely.
Dr. Spartan looks at the gang.
Dr. Spartan: Hey, anybody hungry? How about I order us a bunch of pizzas and we watch a movie in my room? Who's in?
Scooby: Oh! I'm in.
Gang: Ok!
Sheriff Stone: Sure, why not?
They all go in as Velma stops Shaggy.
Velma: We'll be right there.
Shaggy: Like, what's up, Velm?
Velma: Shaggy, I've been thinking about what happened between us at my mom's bookstore.
Shaggy: Yeah, ha, ha, I've been thinking about that, too.
Velma: What I mean is, I just don't have the same feelings for you anymore. But I hope we can still be friends.
Shaggy: Friends?
Velma: I'm sorry, shaggy. Now, let's go have that pizza.
She goes inside. Shaggy is alone.
Shaggy: For the first time in my life, I don't even think pizza can make me feel better. But it's worth a try. Hey, gang! Save a piece for me!
He runs inside to join the others.