Preludes to Ecstasy (1961)

Original title: Kuu on vaarallinen

Sten Lehtoja, a married, middle-aged businessman, picks up a young hitchhiker, Elsie, while driving to his summer home. Elsie spends the night and becomes his mistress. Later during the summer, Elsie also begins an affair with Reino, the teenage son of a local storekeeper. Sten offers to divorce his wife, and Elsie, attracted by the prospect of a secure social position, agrees to marry him when the divorce becomes final. One night when the couple are in bed, Reino climbs a ladder and attempts to force his way into their room; he falls and breaks his neck, and to avoid scandal Sten hides the body. But the strain of guilt ruins the romance, and Elsie contacts the police, who arrest her lover.