On the day of a terror attack in London, GP Mona Harcourt discovers that her brother has been kidnapped in Pakistan and his son Danny has gone missing.
After managing to contact Danny, Mona travels to Lahore to identify Kareem's body. The trip presents an opportunity to reunite with her nephew but also leads her into danger.
Mona returns to Britain and despite being injured, is determined to investigate whether Danny is linked to Islamic radicals but her efforts to get Danny to safety have consequences.
Barnes and the counterterrorism unit are caught in a race against time to foil the imminent terror attacks, but their challenge is made greater still as Mona and Danny are still held hostage.
