Mignight Limited takes place during an eventful nonstop train trip from New York to Montreal. A couple of murders take place, obliging detective Val (John King) to swing into action. There is no shortage of suspects, but Val refuses to believe that pretty Joan (Marjorie Reynolds) is the guilty party-and, of course, his instincts are credit. George Cleveland steals the show as a seemingly eccentric professor, a character obviously inspired by the addlepated religious fanatic in Hecht and MacArthur's Twentieth Century. For reasons best known to the Monogram executives, Midnight Limited is interrupted halfway through with a song performed by hero John King.