A study of the wily brown rat, humankind's unwanted companion throughout the world, whose bite on the world's food resources adds to the growing threat of shortage. In a normal, free-ranging environment, the rat is more than a match for its hosts and colonies flourish. Under abnormal conditions of restricted space and limited food, a rat colony loses all 'social' constraints on behaviour. The film has implicit analogies for all animal behaviour, including humanity's. Plagues, predators and extermination attempts are among the topics discussed.
Ratopolis, Gilles Thérien, provided by the National Film Board of Canada