Malcolm (Ed Lauter) is a clarinet player who inexplicably gave up fame and fortune years ago and has since lived a life of despair and torment. His wife, Lorna (Carole Shelley), is desperate to get him to return to playing so they can save their marriage. One night, Lorna sees light and clarinet sounds issuing from her husband's mouth, and his stomach bulging with a tumor. She takes Malcolm to a doctor (Farley Granger) who removes the tumor, which turns out to be a large alien-like slug. But now Malcolm can no longer play the clarinet. Will he pay the price to regain his creativity?