From the manual:
"Scooby and the gang need your help!
Shaggy, Velma, Fred, Daphne - and Scooby, of course - were on their way to visit Shaggy's uncle. But, as usual, they were side-tracked by a mystery. George and Betty Gob are about to be forced to shut down their amusement park for good - thanks to the Fun Park Phantom - a decidedly unfriendly character who has ruined their business by frightening away customers.
The gang needs your help to sort through the possible suspects and trap the Phantom. This will be a test of your mystery-solving skills and your reflexes - that Phantom tends to chase anyone who starts getting too close to the truth. Be ready - for anything."