Plan Z is one of Sheldon J. Plankton's many plans to obtain the Krabby Patty secret formula and put the Krusty Krab out of business in The SpongeBob SquarePants Movie. It's the last plan under Plankton's disposal.
His plan was to obtain King Neptune's crown, frame Mr. Krabs, in which the punishment would be execution. As Mr. Krabs was frozen at first, and with SpongeBob on the journey to Shell City and Squidward enjoying his time off, no one was able to protect the secret formula, so Plankton stole it, and put the Krusty Krab out of business. Customers came to the Chum Bucket, in which he used to mind control them. He would then rule Bikini Bottom, and renamed it "Planktopolis". However, it was foiled by SpongeBob and Patrick making it to Shell City and back, and then Plankton was arrested and Mr. Krabs was freed, and Neptune got his crown back.
- No one could see in the helmets. It could have blinded them.
- Plankton made the file lemon-scented, possibly as a reference to E.V.I.L. (Every Villain Is Lemons).
- "Plan Z" is also the name of Adolf Hitler's master plan and order in the Second World War during the invasion of the British Navy.
- If Plankton made this plan then how did he only know a-y he might have forgotten though.