Shaggy's uncle disappears and leaves Shaggy with a billion dollars, so Shaggy and Scooby-Doo go to the mansion he left for them and start exploring. They see some of his inventions and then Shaggy sees a note about how his new invention is trying to be stolen by someone and now he must go into hiding. Now Scooby and Shaggy have to go and solve another mystery!