During World War I, the British navy disguised some of its warships as civilian cargo ships, known as Q Ships, in order to fool the Germans. German U-boat commander Capt. Von Haag spots one of these ships, commanded by Adm. Sims, in the English Channel and begins tracking it, leading to a war of nerves between Von Haag and Sims.
| Actor | Role |
|---|---|
| JJ.P. KennedyAdm. William Sowden Sims | Adm. William Sowden Sims |
| RRoy TraversCapt. von Hagg | Capt. von Hagg |
| DDouglas HeraldCapt.-Lt. Stockmar - U-Boat 24 | Capt.-Lt. Stockmar - U-Boat 24 |
| JJack McEwanOber-Lt. Schwartz - U-Boat 24 | Ober-Lt. Schwartz - U-Boat 24 |