A dramatic portrayal of a struggle that is waged annually in wheat-growing areas - man against the wheat rust fungus. Views of the destruction caused during rust epidemics emphasise the urgency with which plant pathologists are endeavouring to breed resistant wheats and, eventually, to annihilate the blight. Animation, time-lapse photography and cinephotomicrography illustrate the life cycle of the fungus and the complex alternation of generations which poses one of the chief problems.