The game, which takes place five years after Maniac Mansion, opens with Purple Tentacle becoming exposed to toxic waste spewing from Dr. Fred Edison's mansion. The toxic waste isn't the by-product of any experiment, it's a device designed specifically to pump toxic sludge out of the building, as it is all the rage with mad scientists lately. Purple's ingestion of it results in him growing a pair of flipper-like arms, vastly increased intelligence, and acquiring a thirst for global domination.