Eighteen months after Russia is blamed for shooting down a new cargo plane over the Atlantic, DS Hana Li is summoned to investigate the murder of an American diplomatic courier at Heathrow. The investigation leads her to London’s US Embassy where new American Ambassador Ronald Tillman is hosting a party. Realising the killer has infiltrated the building, Hana and US Embassy security chief Clay Brody hunt them down. Meanwhile, a Russian threat is received onboard a UK Government jet.