The gang is on the beach collecting clams. Shaggy mentions that Funland is closed, but then all the lights come on, even though it won't open for weeks. They all go to Funland, and everything is running, but no one is there. Freddy knocks down bottles at one of the game booths, and they stack the bottles back up and give him a prize, even though no one is there.
Shaggy and Scooby are playing around when they see a guy walking around extremely fast. They try to find him and Scooby says he can't pick up the scent. Scooby points at the man, and Shaggy turns around to see him go into the House of Mirrors. They play around in the mirrors, and get distracted, until Shaggy sees the robotic figure behind him with glowing eyes. They run outside as fast as they can and hide in the trash cans to get away.
The rest of the gang can't find Shaggy and Scooby and they spot the robot. He gets on the Ferris Wheel and it stops at the top. Fred cranks it down and the man is gone. All the lights go off in the park and everything becomes spooky and dark.
The gang comes together and spots the house of what seems to be the caretaker. Mr. Jenkins, the caretaker, and his sister, Sarah, says that it couldn't have happened and that the moonlight was playing tricks on them.
They leave the house, but go back to the beach to think over their next move. They wait to see if there is anything going on at Funland and nothing happens for the longest time and then suddenly all the lights come back on.
They see that everything is going haywire. The carrousel starts going backwards, the cotton candy machine and hot dog machines start going crazy. They spot the robotic man and follow him, and he tries to get away by throwing stuffed animals. He goes into the tunnel of love and they follow him in. They see him swimming toward them and he rams their boat.
Shaggy and Scooby play around at one of the carnival games and they see the robot. They run as fast as they can and he chases after them. They head for the roller coaster and the robotic man jumps on after them and starts climbing up the cars after them.
The rest of the gang sees them, and Freddy slows another cart full of cars coming the other way. They jump and get away. They see the man on top of the roller coaster and he jumps off and crashes through one of the big tents. He is gone when the go to check it out. They decide to use a bumper car to catch the man and Shaggy turns it on at the motor, so they can't stop. Velma's glasses fall off and they finally stalls when it hits cotton candy.
They set up a trap, but it fails when the robot rams through the wooden wall. He also rams through a brick wall and gets away. Mr. Jenkins confronts the kids and says that the thing that had been menacing them at Funland had really been a robot that he had made. He had wanted to make enough to run Funland, but the robot had gone haywire and started tearing up the place.
The gang agrees to help him and they set up a giant magnet on top of a cart. The robot's metal body will be pulled to the magnet. The robot is being pulled from one of the sheds, when someone cuts the wire and Charlie the robot goes haywire. Sarah is behind a shed and reveals herself. She says that robots shouldn't run a place where children come to play. Mr. Jenkins says he never thought of that.
The gang is at Mr. Jenkins' lab and are talking to Mr. Jenkins. Scooby is getting his ears scratched by Charlie II and the gang laughs.