London. A bomb explodes in a restaurant, where ex-actress Leonora Carr is having dinner. A few days later, a car explodes in front of Laura Cavendish's domestic services agency. Special Security Service agents Peter Stone and Nick Marriot lead the investigation under the orders of James Pascoe, head of the Triple S. Omega, also a Triple S agent leading a double life, becomes part of the undercover mission as she poses as the ex-actress to infiltrate the plans of a drug dealer financing terrorist operations. Stone and Marriot follow her and grow captivated by Omega's beauty and intelligence. The operation leads the agents to a siege at a Surrey farmhouse. When the terrorist plot touches upon the highest echelons of government, Omega takes matters into her own hands.