Synopsis:
A small deserted island off Scapa Flow which has a wartime naval fortress that has now been taken over for top secret weapons experiments. Four able seamen arrive having volunteered for the duty. The sailors decide to nickname the island Sorrento. They find to their dismay that the Petty Officer in charge of them is P.O. Herbert, who has a bad reputation around the fleet. He is a strict and so has the men resenting him. Herbert takes a shine to the youngest able seaman - Turner - nicknamed "Sprogg" and orders him to his cabin for cleaning duty. Sprogg comes back later with a bar of chocolate. Able Seaman Turner "Lofty" is very worried about Herbert's attentions to the younger man. Another Able Seaman arrives - Hudson. In the War he had been working on radar. He is excused some duties and works on the secret weapon. Herbert tries to get Sprogg to tell him what the men are saying behind his back but he refuses and so is given the task of removing rust from ladders. Lofty is appaled and confronts Herbert but before they resort to blows there is an explosion and Hudson is killed. Another sailor is sent to the island who turns out to be the man who ran away with the wife of one of the other sailors. The trial of the weapon is due and a volunteer is called for. Lofty rigs is so that he is the one to go. Whilst he is on board a ship waiting for the trials to begin he tells the Sub-Lieutenant about Herbert. When the trial has finished the sailors are given leave and P O Herbert is sent to another island where the trials will continue.
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