It is late summer in London. Leonard Deppling returns to the capital from Scotland, where he has spent the past year nursing his dying father. Missing from the funeral was his younger brother William, who lives in the north of the city with his wife and two young sons. Leonard is alone, and rootless - separated from his partner, and on an extended sabbatical from work. He moves in with William, hoping to renew their friendship, and to unite their now diminished family. William is a former lecturer and activist - serious, defiantly unworldly and forever questioning - a man who believes that happiness and freedom come only from knowing oneself, and who spends his life examining the extent of his ignorance: running informal meetings and symposiums with ex-students and local residents. Leonard realises he must once again drop his expectations about the norms of brotherhood and return to the 'island of understanding' the two have shared for so long.