Overview: Chief Supt. Franks looks into a hijacking of a plane in Edinburgh where the pilot has vanished which could be linked to the disappearance of terrorist Gabrielle from Paris.
Overview: French intelligence send pictures that show hit man Constant Delangre acting as Gabrielle's bodyguard and she likely to be the mystery passenger on the plane that landed in Edinburgh.
Overview: Capt. Aubrey Percival from SIS takes over command of the case. Franks discovers Gabrielle was a Soviet agent but is disillusioned. A hit man is already on her tail in Scotland.
Overview: Chief Supt. Franks is under pressure from Special Branch while Captain Percival is playing politics. Franks finds warns Gabrielle that a hit man is on her tail.
Overview: Special Branch take over the protection and surround Gabrielle's home. Frank's men track the hit man down to a caravan but he murders two people and slips the net.
Overview: Assassin Constant Delangre is shot dead by a sniper before Special Branch arrive with the evidence that Gabrielle is housemate Agatha, is actually communist agent who will stop her leaving for Canada.