Herbert Marshall as Dr. Stephen Dominik

Ruth Chatterton as Professor Anna Mathe

Simone Simon as Marie Claudel

Constance Collier as Professor Augusta Wimmer

J. Edward Bromberg as Dr. Spindler

Dixie Dunbar as Luisa

John Qualen as Toni

Shirley Deane as Fritzi

Tyrone Power as Count Vallais

Frank Reicher as Dr. Hoffenreich

George Hassell as Dr. Wilfinger