Plan Z is to obtain King Neptune's crown and frame Mr. Krabs, in which the punishment would be execution. As Mr. Krabs is frozen at first by Neptune, and with SpongeBob and Patrick on the journey to Shell City and Squidward enjoying his time off, no one is able to protect the secret formula, so Plankton steals it and put the Krusty Krab out of business as a result.
Customers come to the Chum Bucket, in which he uses bucket helmets to mind control them. He rules Bikini Bottom and renames it "Planktopolis." However, it is foiled by SpongeBob and Patrick making it to Shell City and back, and then Plankton is arrested, Mr. Krabs is freed, and Neptune gets his crown back.