Scarlet Week.

After a weekend of dancing and camping on a recreation island near the city, a young factory worker decides to stay and cut work for a day. Walking around the now deserted island, he meets a beautiful woman camping alone and sunbathing in the nude on the beach. A hot romance flares up between the worker and the more upper-class married lady, lasting through the light-filled nights of the whole summer week until the woman's much older husband returns to the island the next weekend.