Zim goes on an outing to the downtown area in order to test a new guidance chip he installed in GIR, but when GIR removes the chip before leaving in order to store a cupcake, Zim and GIR are left lost and have to resort to public transport to find their way back. Their journey home is complicated further by Zim temporarily losing his vision by looking at the sun, his disguise being mistaken for that of a bank robber, and his escape from the police being wrecked by GIR replacing his extra rocket fuel with tuna fish.

When it begins to rain one day, Zim becomes worried because he’s never experienced rain before. Dib takes notice of his fear and he coaxes Zim into stepping into the rain, only to discover that the Irken race has an innate weakness to water, which causes a burning sensation upon impact. Dib decides to exploit this new fact to create the ultimate weapon to stop Zim once and for all, but Zim himself attempts to find a way to protect himself from this new found weakness, which all leads up to a confrontation that neither of them would have expected.

When Zim comes home from a lousy day at skool because he found out that Dib knows a flaw in his security system, Gir attempts to cheer him up by rubbing bacon oil all over his face. However, when Zim develops a pimple due to the grease, he fears that he will be considered abnormal and that it will jeopardize his mission. Zim believe he can use some acne medicine to get rid of the pimple, but when it only gets worse and when Gir draws a little face on the pimple, Zim believes all hope is lost; though Zim soon discovers the pimple has hypnotic powers and he hopes to exploit this new power in order to get Dib to reveal his secret.