When at skool one day, a child comes into class late because his head was itchy, which Ms. Bitters recognizes that it was due to lice. Before she can do anything, however, the lice infect the rest of the students in the class, so Ms, Bitters informs the Delouser, who proclaims martial law and the children are taken into separate rooms. However, Zim shows no sign of being infected by the lice, which causes the Delouser to take special interest in him.

When Zim attempts to taint the Earth's cow-meat supply with sewer water is ruined because of Gir's antics, he decides to increase the power on Gir's behavioral modifier, which will permit him to stay in serious mode all the time. However, when the serious Gir starts to consider Zim a threat to the mission and runs off to learn things on his own accord, it's up to Zim and Squidman to find Gir and turn down the power on his behavioral modifier before too many individuals see them and jeopardize their mission.