The film's plot is simple enough: On the night of a full moon, at a Swiss chateau from whose gate hangs a sign insisting PASSAGE INTERDIT, a command the camera immediately ignores (anticipating the opening shot of Citizen Kane), two
douroucouli monkeys escape from their owners, both of whom are represented metonymically almost exclusively by hands, feet, and shadows.
Other important species of forest monkey in the rainforest include the
douroucouli, or night monkey (Aotus trivirgatus), the dusky titi (Callicebus moloch), the monk saki (Pithecia monachus), the brown capuchin (Cebus apella), the spider monkey (Saimari sciureus), and the red howler monkey (Alouatta seniculus), whose cry is amplified by a special adaptation of the larynx that acts as a resonator.
