Dylan and Brenda are setting up for Volleyball, but are kidnapped by a Man Crab.
The gang are ready to watch the Volleyball. They pass Bud Shelton, the person who sells water because Shaggy wants to purchase junk food, but Velma thinks otherwise. She taunts him by asking the grumpy Skipper Shelton about his nose, which was eaten by a clam. The Man Crab kidnaps ladies during the game. It escapes into a tent, were Skippers locker lies, so Skipper is a suspect. The police come, but refuse to close the beach. Fred sets up a simple trap. Shaggy sneaks off for some junk food but is caught in Freds Trap. Daphne, who will play, is chased by Man Crab and passes the trap. The Man Crab kidnaps Daphne and Velma is angry at Shaggy. Fred digs and digs everywhere, even indoors. At the radio station, he says he won't stop until Daphne is safe. They head to the library and discover the original Mystery Incorporated disappeared in the Crystal Cove Caves. In the caves, the Man Crabs victims are in a cage. The gang free the victims, but are chased through the caves by the Man Crab. Shaggy and Scooby finally are nearly trapped until they lead the Man Crab into Freds Trap. Bud Shelton is the Man Crab so he could get revenge on Peter Trickell for stealing his idea of non fat water.