Mystery Inc. is no more. Fed up with their differences and conflicting egos, the gang split up and go their separate ways…

Two years later, each of the ex-members receives a mysterious letter, inviting them to come to Spooky Island amusement park. The owner, Emile Mondavarious, is worried about the state of his guests as they leave his park; local myths say the island is haunted, and he wants the gang to reunite and solve the mystery. The gang start of trying to solve the mystery individually, but eventually find themselves reforming Mystery Inc. once again.