The penultimate season of the hugely successful, long-running drama introduces a host of new characters. There's Beth Bailey, a brilliant ex-mercenary who was posing as an Eastern European prostitute when she ran into the team. Dimitri, an ex officer in British Special Forces, has been recruited for his skills in fighting terrorism on the front line. And finally, data analyst Tariq has been fast-tracked through the system. Young, bright and keen, he's a true computer whizz and what he lacks in experience, he makes up for with natural brilliance. Meanwhile the usually calm, confident Harry is caught in a difficult position when he is forced to work closely with the Russians. Relations between the CIA and MI5 reach a breaking point over mysterious hackers. And a horrific truth about Lucas' past is uncovered by Harry when they come face to face in a compelling interrogation. Friendships are tested to the limit, Harry and Ruth's bond intensifies and the depth of deceit leads to the ultimate game of cat and mouse.