The story centres more on his daughter Enid and his old friend Edward Malone. Another friend from the 1912 novel The Lost World, Lord John Roxton, is also involved in the novels second half. Professor Summerlee, who has died of old age around this time, is referred to by the mediums. Heavily influenced by Doyles growing belief in Spiritualism after the death of his son, brother, and two nephews in World War I, the book focuses on Edward Malones at first professional, and later personal interest in Spiritualism.