When school lets out for the summer, T.J. Detweiler is ready to play hard. When all his friends head off to summer camp, though, he’s left without anything to do. One day, passing by the empty shoolyard, T.J. notices an eerie green light emanating from the main building and attempts to rally his parents and the local police to investigate. When he’s dismissed as a bored kid with an overactive imagination, he turns to the principal of the school. When the principal is dematerialized while investigating the green light, T.J. calls his friends back from summer camp.

At first skeptical of T.J.’s story, the gang become believers when they see a giant weapon emerge from the school’s roof and fire a laser beam into the sky. Their school and principal in obvious danger, the gang decides to sneak into the school to investigate, but they are quickly discovered by the bad guys, led by an evil renegade ex-principal. In the chase that ensues, T.J. is captured. All seems lost, until the gang gather together every kid they know, and with the help of their teachers, vow to take back their school.