The crew of HMS submarine Sea Tiger have their leave (and assorted family problems) cut short when they are recalled for a special mission: sink the new German battleship Brandenburg. En route, they learn that their target has entered the heavily defended Baltic; rather than fail, they follow it. Tension builds as they approach their target. After the attempt, escape seems impossible…unless they can refuel in enemy waters.
Action | Drama | War
| John Mills | … | Captain – Lt. Taylor, R.N. | |
| Louis Bradfield | … | First Officer – Lt. Brace, R.N.R. | |
| Ronald Millar | … | Third Officer – Lt. Johnson, RNVR | |
| Jack Watling | … | Navigating Officer – Lt. Gordon, R.N. | |
| Reginald Purdell | … | Coxwain – C / P.O. Dabbs | |
| Caven Watson | … | Chief Engine Room Artificer – C / P.O. Duncan | |
| Niall MacGinnis | … | Torpedo Gunner’s Mate – C / P.O. Mike Corrigan | |
| Eric Portman | … | On Hydrophones – L / S. Hobson |