Time-lapse photography helps us appreciate the marvellous seasonal changes undergone by a large oak tree. These changes also affect the many animals and insects that feed and live in the tree. Among other things, the film describes how the tree nourishes itself during the growing season, how it synthesizes various elements during the day and at night. The tree and the creatures who inhabit it form an impressive microcosm, kept in good health by natural checks and balances.