This film sketches the fascinating behaviour of long-tailed macaques in a research unit. Detailed observations - e. g. object manipulation when throwing stones into a pond or the facial expressions used in agonistic interactions - are embedded in the context of technical, ecological and social intelligence. In several chapters the film explains how a rich behavioural repertoire of the animals, ambitious animal husbandry and fascinating behaviour research depend on each other. The film is likewise suitable for school classes preparing a zoo visit, for students of zoology and animal keepers.