Harold Makepiece, a
redundant Civil Servant, while taking a quiet holiday at the seaside, gets into
conversation with Joyce, whose main preoccupation is feeding sparrows, in whose
welfare she seems to take a somewhat exaggerated interest. What starts as an
odd but moderately reasonable exchange gradually turns into a nightmare as
Harold becomes involved also with a freakish Edward and the seaweed-eating
Sandra. It turns out that all three are planning to bomb a large power station
nearly because of the pollution it causes. They try and rope in Harold as an
accessory, until events are taken out of all their hands in a totally
unexpected way.