Kenya, 1947. A hunting expedition led by American writer John Remington makes a startling encounter, and then vanishes without a trace. Shortly afterwards, Katherine Austin, agent of the British Secret Intelligence Service, arrives in Mombasa. Her mission: investigate a series of mysterious sightings and incidents, of which the disappearance of the Remington party could be the latest. Undercover as a teacher, courted by colleagues who may be working for competing secret services, she's about to enter a whole new reality.