Lizzie, Miranda and Gordo all have big problems on the day their pictures are to be taken for the junior high yearbook. Lizzie searches and searches for the right thing to wear, but her mother insists she put on a ""hideous"" sweater that her grandmother gave her. Miranda runs afoul of Kate when they both show up wearing the same outfit. And Gordo feels the pressure to assume a tough-guy pose when his picture is snapped. Meanwhile Matt hasn't studied for a quiz at school, so he fakes being sick to get out of it. But he finds out that his mom's cure can be worse than the disease.

The various obsessions of Lizzie, Matt and Gordo are driving friends, family, teachers and themselves to distraction. Gordo is intent on winning the Science Olympics at all costs against defending champion Larry Tudgeman. Matt becomes hall monitor at his school and gets carried away with his own power, giving out citations to schoolmates by the dozen and even trying to do the same to teachers and family members. Meanwhile, after she and Miranda work on a successful volunteer project at school, Lizzie becomes an environmental warrior, a fanatic for collecting clothing and food for the homeless, and even a vegetarian! All three learn that they must put limits on their fanaticism or else their original causes will suffer as a result.

Gordo has his camera and is filming Lizzie and Miranda in the school cafeteria. He forgets the camera when they leave, and when he goes back for it, he finds it was running the whole time. When the friends view the footage, they see Kate telling Claire a big secret--she's fourteen, a year older than the other seventh graders, because she was held back in kindergarten! This gives Gordo an idea. He sets up several hidden cameras around the school which catch lots of embarrassing moments on tape. Gordo plans to make a movie and enter it in a local competition, hoping to prove with it that even the popular kids have things to be embarrassed about.