Hiding, lying in wait on the sea bed, is XE16, fifty-four feet long with no defensive armament but one of the most important ships in the Royal Navy. Her four man crew, fresh from raids in Norway where they were used to distract the Nazis from the D-Day invasion, know that the outcome of the war could depend on them and their fellow midget submariners.
The action begins when the Germans hide their new rocket on a ship in a Norwegian fjord. Lt. David Seaton and his crew sinks the ship only to later return to that very ship, to recover a secret device from it and pick up a defecting scientist. Seaton and his crew return to base bruised and bloodied but undaunted only to be given an even more dangerous mission: to blow up an underwater U-boat pen and rocket-launching site on the Normandy coast.
In many respects this is a fairly predictable piece of story telling set beneath the North Sea. There is the almost obligatory love interest, there is boredom, discomfort, jealousy and bickering on board set alongside acts of selfless daring. However, it is also a solid piece of writing providing a certain escapism that will no doubt charm fans; whilst it may spark a desire in casual readers to look more closer at the true facts behind the story.