The story is told through the viewpoints of Lieutenant Robin Savage and the innocent but determined Anne Hildreth, although Savage's viewpoint predominates later in the novel. It begins in 1879, when Britain and Afghanistan are engaged in the Second Anglo-Afghan War.
Anne Hildreth and Robin Savage have met and become attracted to each other before the narrative starts. Anne is the daughter of a Commissariat officer and is travelling with her parents to the military post at Peshawar in the North-West Frontier Province of India. En route, she witnesses the murder of an Afghan stranger. In his last moments, the murdered man writes the word "atlar" (horses) in his own blood.
Meanwhile, Robin is part of a military column in Afghanistan. He is the son of a distinguished soldier and has almost been forced to follow in his father's footsteps, but has no particular thirst for action. As the result of an accident, and a superior officer's bungling, he is accused of cowardice, and is also sent to Peshawar to await a military court of inquiry.
Life threatens to be awkward, but an acquaintance, Major Hayling, connects the murder witnessed by Anne with a trophy recovered from a dead tribesman by Robin in Afghanistan, a jezail with the words "atlar shimal" (horses, north) engraved on it. Realising that Robin's true passion is for solitude and empty spaces, Hayling recruits him into the Secret Service and sends him in disguise into Central Asia. Accompanied by a faithful Gurkha orderly, Robin sets out to discover the motive behind the murder and determine whether it is connected with the ambitions of Tsarist Russia. Before departing he marries Anne.
Ultimately returning to British India, Robin is reunited with his wife and infant children. He is decorated with the Distinguished Service Order in recognition of his achievements, and appears to have achieved conventional success. However, he disappears across the frontier again in pursuit of his semi-mystical goals. Anne is left to accept the unbridgeable divide between herself as the Lotus and Robin as the Wind.
