Meteorologist Arthur Pilbeam's fiancée Betty, breaks their engagement because he does not spend enough time with her due to having to attend at the BBC every hour, on the hour, for his vital job of creating the
BBC pips. He is so upset, he uses the pips to play "
Shave and a Haircut". When he is reprimanded, he tries to resign, but this is refused, but when he says he wants to avoid all women, he is posted to a remote
Scottish lighthouse to make weather reports. Before taking a boat from the mainland, he is warned by the locals that he will go mad from the isolation and the curse of a
mermaid within a month, as his predecessors have. He still goes to the island, but as soon as he lands he is disturbed as most of his baggage disappears. Pilbeam realises he is not as isolated as he thought and meets Jane, a young girl who
stowed away on the boat that brought him to the island, and then Bobbie, a model and the sole survivor of a torpedoed ship. His radio disappears and Bobbie sees a man tied up in a cupboard, but he also seems to disappear when she shows Pilbeam. Another boatload of women plus some crewmen, arrive from Bobbie's ship. This makes it very crowded in the lighthouse, until people start to mysteriously disappear during the night, leaving an anxious Pilbeam trying to discover what has happened to everyone. It turns out that Nazi agents have been secretly sweeping the nearby waters of mines and have taken everyone else prisoner. They leave Pilbeam free and force him to send away a rescue party without arousing suspicion. But between Pilbeam, Jane's uncle (from the neighbouring island) and the women, they manage to turn the tables on their captors. They tie the Germans up and set out on the German boat. On the way back to the mainland, however, they come across an enemy warship in the fog. The Germans mistake them for their own spies and order them to guide them through the minefield. Their small boat is able to avoid the mines but the ship strikes a mine and sinks. Pilbeam returns to London a hero, to find Betty has been given his old job on the pips. Having apparently rebuffed him, she plays "Shave and a Haircut" and he rushes off to see her. ==Cast==