When Liz tells Caitlin about her interest in animal testing, she tries to convince her to write an article for the school paper. Liz and Caitlin work together in order to let the students know about this topic. When Kathleen informs Caitlin that animal testing is necessary in some cases, Caitlin does some research and learns that Kathleen is right.

While working on a science fair project together, Melanie is shocked to read in Kathleen's diary about her diet. It appears that Kathleen is anorexic, which causes her to faint during the science fair. Kathleen is furious with Melanie when she tells Ms. Avery. Ms. Avery insists that Kathleen talk to the school nutrionist.

Arthur doesn't like his father's new girlfriend, and him and Yick plot to break them up. Arthur is frustrated when his attempts don't work, and is shocked to see that his father's girlfriend had spent the night. At the school open house, Arthur is furious when his father brings his girlfriend. Arthur feels bad when his father later tells him that he broke up with her.