A 1930s British summer Bank Holiday starts at midday on Saturday with a rush for the trains to the seaside. Doreen and Milly are off to a beauty contest, Geoffrey and Catherine are having an illicit weekend in the Grand Hotel and May and the kids are set for a more straightforward holiday of sea, sand, and pub. Meanwhile, the manager and performers on the pier are praying for rain.

Unsuccessful writer Aylmer Franklyn takes the chance to change identities after he discovers a corpse. However, he soon finds himself accused of the murder of a maid at a near-by boarding house.