Plain Clothes follows the story of Nick Dunbar, a high school student who goes undercover as a new student to solve a murder case. The cast of the movie includes Arliss Howard, Suzy Amis, George Wendt, Diane Ladd, Seymour Cassel, Larry Pine, Jackie Gayle, Abe Vigoda, Robert Stack, Alexandra Powers, Peter Dobson, and Loren Dean.