During World War I, a female agent tries to unmask a German spy.
| Actor | Role |
|---|---|
 Constance BennettFrances Hawtree / Z-1 | Frances Hawtree / Z-1 |
 Erich von StroheimValdar / Schiller / Blecher | Valdar / Schiller / Blecher |
 Anthony BushellCapt. Arthur Chamberlain | Capt. Arthur Chamberlain |
 William CourtenayMr. Yates | Mr. Yates |
 Crauford KentGeneral Hewlett | General Hewlett |
 Charlotte WalkerLady Catherine Chamberlain | Lady Catherine Chamberlain |
 William HoldenSir Winston Chamberlain | Sir Winston Chamberlain |
 Paul Panzer'Kirsch' the Decoy (uncredited) | 'Kirsch' the Decoy (uncredited) |
 Wilhelm von BrinckenCapt. Kugler (uncredited) | Capt. Kugler (uncredited) |
 Ullrich HauptGerman Colonel (uncredited) | German Colonel (uncredited) |