London during a blistering heatwave. A man wakes in the middle of the night, hearing noises from downstairs. He assumes it's a burglar - nothing prepares him for what he finds.

Across the city, DI Leah Hutch and DS Benjamin Randle are called to a murder scene outside their jurisdiction. A woman has been killed - the only suspect, a friend from Leah's past who refuses to speak to anyone but her. Meanwhile, fourteen-year-old Zed Okoro's mother has vanished.

He will do anything in his power to find her - even if it means risking his own life. As Leah and Randle investigate, they discover a conspiracy with roots far from home. Three incidents.

One connection. What secrets make people kill?