Powerline

When Shirley (an undercover agent) is killed in some lonley woodland, Fred and Tessa investigate posing as 'travellers' and join a band of nomadic religious freaks camping rough on Lord Leydon's estate. Tessa goes to Manor House to visit the impoverished James Leydon who already suspects her of working with the 'thought police'. A 'friend' of Jamie's, Barbara Dalchley, turns out to be in league with Sergei, a Russian defector, and Seth, one of the 'travellers' whose mission is to take pictures of nuclear missile bases. A security patrol around the estate rescue Fred and Tessa when their camper van is sabotaged, and the episode ends with Tessa involved in a shoot-out.