Season 1

Arms dealer Giles de Vere is prompting NATO's latest weapon known as "Bright Star". Captain Percival has got wind that de Vere selling to the Soviets, via Switzerland so has tampered with the missile on a routine check..

Journalist Malcolm Russell gives out addresses of British intelligence operatives in a newspaper article. Ewan Benman's friend is murdered and he wants revenge. Cap. Percival needs to Russell alive for the greater good.

Sir Robert Constable dies in a taxi on the way to meet Krotkin, USSR spy. Captain Percival believes he is not what he seems and conspires with CIA officer Colonel Elliott to give the Soviet Union what they believe they are getting.

Syria terrorist Dr. Mohammed Riffi thinks he is dying from Berners Syndrome and travels to Rome, without bodyguards, to see his daughter. On the train he meets Capt. Percival who uses his religious believes to his own ends.

Two fake British passports flag up a possible terrorist attack using a bomb. Learning that the pair came via Turkey, Capt. Percival and his team gamble that the attack is meant for a hard line Israeli minister going to Checkers.

Soviet civil servant Yuri Semanov wants to defect to the British as a major source of information. Unsure, Capt. Percival puts together a dossier that would see him shot as a traitor but enough to make a valuable asset in future.

Radio producer Richard Ellison accuses, Armenian born, announcer Jane Minto of secretly passing messages to terrorists in Europe. Percival knows Minto is a double agent working for him and it's Ellison who is a KGB agent.

Debutante Sophy offers to help SIS after she meets a famous musician who works for the KGB. A plan to offer the Soviets a fake version of the Microfish system, designed by ex-boyfriend Frank Liscombe, backfires when he vanishes.