Wrongfully convicted of a robbery and murder, Paul Lavond (Lionel Barrymore) breaks out of prison with a genius scientist who has devised a way to shrink humans. When the scientist dies during the escape, Lavond heads for his lab, using the shrinking technology to get even with those who framed him, and vindicate himself in both the public eye and the eyes of his daughter, Lorraine (Maureen O’Sullivan). When an accident leaves a crazed assistant dead, however, Lavond must again make an escape.