A story involving time travel, it concerns a secret society whose aim is to avert World War I to preserve and expand the British Empire.

A shadowy group called the Otherhood buys his stamp and takes control of the time machine, which it wishes to use to preserve the existence of the British Empire.

Denys Winterset, a promising young official in the Colonial Service in Africa in the 1950s, travels the Cape to Cairo Railway, where he meets a mysterious stranger, and is invited to join the Otherhood.

Winterset is told that he must travel back to the beginning of the group in 1893 and assassinate its founder Cecil Rhodes.

He helps his older self escape from Africa amid the chaos and returns to London, where the story ends with their last meeting many years later.