The story follows a man who finds that a double of himself has moved into his apartment and is taking over his life. A pushy fellow named Peter mistakenly dials his own telephone number in a bar and is astonished to find a nice guy named Peter answering at the other end. Peter is ‘both victim and victor of a brief struggle for the custody of a soul.

Life is sure getting complicated for Bill Lawry (Robert Klein). His company is seling a new line of medical equipment and poor Bill has just one week to memorize 67 new products. Biothermic dilator, Electromyograph. Entero-something-or-other. He studies until the wee hours and falls into a fitful sleep. Next morning, as he leaves for work, his neighbor happily informs Bill that his dog Ginger had her litter last night. There were nine puppies, "and that's quite a few for a small dog like an encyclopedia." Huh? A puzzled Bill heads for the office, where a young co-worker asks his advice on a good place to take a pretty girl for dinosaur. Come again? That afternoon, Bill hears people saying things like, "Wine mental eight van cattle renting jupiter." Everybody but Bill has a new vocabulary!