Witold just failed his law-school examinations and Fuchs has just quit his job at a Parisian fashion company. Arriving for a few days away at a so-called family guest-house, they are greeted by a series of unsettling omens: a sparrow hanging in the forest, then a piece of wood in the same condition, and finally signs on the ceiling and in the garden. In this guest-house there is also a baleful mouth, that of the maid, and a perfect mouth, that of the young woman of the house with whom Witold falls madly in love. Unfortunately, she has just married an architect of the most respectable sort. But is the young woman equally respectable? The third hanging, that of the cat, is Witold's doing. Why did he do it? And above all - will the fourth hanging be that of a human?
