London 1943. An Old Bailey judge explains that this story illustrates many similar cases that arose during the war.

1941. In Piccadilly during an air raid, Naval Intelligence Captain Alan Pearson collides with WREN Diana Fraser in the blackout. Taking cover in a doorway, Diana tells him she was making for Waterloo station to re-join her unit. He invites Diana to shelter in his Piccadilly flat.

Against the sound of bombs, Alan plays a boogie tune on his piano to drown the noise, and Diana tells him of her pre-war career as dancer. They are clearly attracted to each other, and Alan invites her to stay in his sister's room overnight

Next morning Alan sees Diana off at Waterloo station, where she is greeted by her navy pal Sally Benton as 'Sunshine'. Diana is the star of the corps de ballet of HMS Falcon, who perform for an appreciative audience. In the navy, Diana has an admirer in Canadian sailor Bill Weston, who insists on meeting her in London.

Diana phones Alan saying she has 48 hours leave, and he meets her at Waterloo station. Diana also arranges to meet Bill, who asks her to marry him, but she declines.

Diana and Alan visit a nightclub, where Diana receives a phone call that she is to be posted to the tropics in 72 hours. Impulsively, Alan proposes, and they marry at Caxton Hall, followed by a visit to a restaurant where Alan's father (a judge) is at an adjoining table. Alan tells him they are married. Back at the flat and deeply in love, Diana and Alan look out at the searchlights over London and dance. Next morning he sees her off at the station.

In Singapore, Diana and Sally work as radio operators until they are evacuated on HMS Alcestis. After warnings, their ship is torpedoed and the survivors include Diana, Sally and Bill. Adrift in a small boat, they see a tropical island and land there. They hear of the fall of Singapore on their radio and cook fish, dance tangos and sing songs round the campfire. Diana rejects Bill's repeated sexual advances.

Alan, on a mission in Tobruk (where he receives a leg wound), receives a telegram to the effect that that Diana is 'missing believed drowned'. Back in England, he is visited in hospital by his father, who has no further news.

Time passes and it is spring. Alan gets into conversation with US service personnel sitting outside on the grass while he recovers at the family country seat. His sister Virginia invites one of them, Joan Draper, to tea. Joan tells Alan that her fiancée (a flier) was killed. Alan and Joan go boating, fall in love, marry and have a baby son.

After three years, the shipwrecked survivors build a boat and flee the island. They are rescued and Diana flies to England via New York. Diana is surprised there is nobody at Waterloo to meet her.

Alan's Piccadilly flat has been bombed, and the porter gives Diana a forwarding address, together with her letter which had not been forwarded. After buying a new dress, Diana visits Alan's family home, and is welcomed by Joan. Giving her name as 'Sally Benton', Diana is shocked to hear that Joan is now Alan's wife, and after seeing their baby son, leaves in a hurry. Diana visits Alan's father at the Old Bailey for legal advice.

At a Navy concert, Alan is the piano soloist in 'Piccadilly 1944', which triggers many memories. Diana arrives at the hall. There is an air raid alert and the audience evacuate. As bombs fall, Diana goes backstage, and on seeing her, Alan is in a state of deep shock. Diana asks for a divorce, and falsely tells him she has 'found somebody else'. There is a direct hit and Diana is injured.

Alan visits Diana in hospital where she is dying, and she admits it was all lies about 'another'. Alan kisses Diana, and she dies.

1943. Summing up, the judge says that the death of Diana has allowed Alan and Joan to legalise their union by remarrying, but the application for legitimacy on behalf of Alan's son must fail.