When newly weds Jack and Peggy face eviction, they are tricked into buying a run down houseboat. After rebuilding the engine, they take their friends Sid and Sandra, on a local trip down the river to Folkestone, but somehow they end up in France, and with no fuel and supplies, they resort to desperate actions to get back home.

Travellers on a trans-European train are delayed for a night due to bad weather in a small fictional country called Mandrika. The passengers cram into the small village hotel where socialite Iris Henderson meets an old governess called Miss Froy. Shortly after the journey restarts, Miss Froy disappears.