Dexter has created the ultimate invention - The Clone-a-matic - but his older sister Dee Dee has meddled again and accidentally cloned herself. And, there's not just one of her. Dexter's Laboratory is infested with mini-Dee Dee's bent on destroying Dexter's wonderful experiments - what a nightmare! It's up to players to help Dexter catch the Dee Dee's, put his lab back to normal, and get Dee Dee back to her single self before Mom calls for dinner.