CIA agent, Jason Price and his wife, Kellie, arrive in London for a long overdue break. After having lunch at the top of The Shard, an explosion near Buckingham Palace sends the capital into chaos. Special Branch agent Blake Langford is on an assignment in France and watches the explosion happen on TV. Local detectives discover that it was a terrorist attack by an American journalist targeting The Royal Family. As the smoke rises over Buckingham Palace, Jason Price's vacation is over before it even begins. Rushing to the scene, he uses his CIA credentials to gain access to the investigation where he quickly learns that British Intelligence is scrambling to contain the crisis. The Royal Family has been moved to a secure location but the attack has left the country on high alert. Meanwhile, in France, Blake abandons his undercover assignment and returns to London. As he digs deeper into the investigation, he discovers the journalist, Daniel Carter, had been working on an expose about a covert MI6 operation before disappearing several months ago. Now he has resurfaced as a terrorist leaving cryptic messages across London's shadowy underworld. When Kellie Price becomes a target, Jason's mission turns personal. With London on the brink of another attack, Jason and Blake must work together to stop a conspiracy that could shatter the fragile alliance between the USA and the UK before it's too late.