A bear and a rat explore dark forests, treacherous ravines and snow-swept glaciers. With no real aim in mind, the bear and the rat bungle along in a folk tale of their own devising, wondering what they should do and where they should go, enjoying nature together, foraging for sustenance, getting lost, squabbling, joking and making music along the way.

Artists Peter Fischli and David Weiss create the ultimate Rube Goldberg machine. The pair used found objects to construct a complex, interdependent contraption in an empty warehouse. When set in motion, a domino-like chain reaction ripples through the complex of imaginative devices. Fire, water, the laws of gravity, and chemistry determine the life-cycle of the objects. The process reveals a story concerning cause and effect, mechanism and art, and improbability and precision, in an extended science project that will mesmerize the mind.