When the boys build an Anti-Gravity Fun Launcher, Carl accidentally intercepts their plans and assumes they are working for Dr. Doofenshmirtz, so he is sent undercover to figure out what they are doing. Meanwhile, Perry tries to find a lost agent, and Dr. Doofenshmirtz also acquires the blueprints to help with a parking issue on his street.

After watching a sci-fi movie marathon, Candace becomes convinced that Ferb is an alien. Meanwhile, Dr. Doofenshmirtz tries to market an evil invention by claiming it to be a cleaning device.