Flight Lieutenant Peter Romsey, a RAF navigator, is one of Lifeline’s latest customers and London are anxious for his swift return – his technical knowledge of the Oboe navigation system is vitally important. Natalie takes Romsey and other evaders down the line, but Romsey is separated from the others and takes the wrong train, finding himself lost in the French countryside. As Lifeline tries to track him down, Romsey finds unexpected assistance from Hugh and Dorothy Neville, an expatriate English couple. A celebrated author utterly disillusioned with the war, Neville must decide where his true loyalties lie when Romsey turns up on his doorstep.

In the aftermath of the Romsey business, a German newspaper publishes British military secrets. Curtis decides that the traitor must be found and dealt with. He travels to France and retraces Romsey’s steps. Meanwhile, Albert is still suspicious of Curtis and decides that once he is away from Brussels he will reveal his true colours. Monique follows Curtis to France to watch him and finally prove whether he is trustworthy or not, while Curtis’ investigations lead him to the Neville residence.

Following up a lead in their continuing investigations to crack the evasion lines, Kessler and Brandt examine the details of a recent murder case in France with Curtis, in his cover as a travelling salesman, as their prime suspect. Believing Curtis to be part of the resistance, Brandt and Kessler visit the Candide and take him away for questioning. With their efforts to help evaders becoming more and more dangerous and difficult, Albert and Lisa fear the worst, as the Germans strike right at the heart of Lifeline.

Some months have passed, and Albert and Monique are preparing for the grand opening of the Restaurant Candide on Brussels’ Grand Place, financed by London to allow Lifeline to continue its activities. Lifeline also recruits a new forger, Max Brocard. Alain brings a British agent to the Candide with an urgent request from London: a Brigadier General with information on a major Allied offensive in North Africa (named in the programme as Operation Torch) has been shot down on his way to a top secret meeting and must be rescued at all odds. Natalie has already discovered the Brigadier and prepares to take him down the line. However, disaster strikes when a German soldier is murdered, and in retaliation, Kessler orders that twenty people are to be held hostage and shot if the killer doesn’t give himself up. The Brigadier is one of the hostages.

Whilst dining at the Candide, Kessler becomes intrigued by Madeleine Duclos, an elegant but remote socialite. Meanwhile, Monique takes some airmen down the line and is shot and wounded when she becomes unintentionally involved in a smuggler’s attempt to evade a railway checkpoint. Recovering in a convent hospital, she is cleared of smuggling, but finds herself in more danger when the French police discover the train tickets she was carrying for the airmen and that her papers are false. Kessler sets out from Brussels to interrogate her, prompting Natalie, Alain and Max to stage a daring rescue mission.

Kessler is enjoying his developing relationship with Madeleine, but begins to feel that his feelings for her may cloud his judgement while Brandt is once more approached about joining the military plot to assassinate Hitler. The British co-ordinate a massive air raid attack on Berlin, but bombs are dropped on civilian targets in error – with tragic repercussions for Brandt. Monique and Alain try but fail to help a bomb aimer shot down on his way back to England. Having captured the man, Brandt finds himself face to face with the enemy and this time, it’s personal.

At Gestapo headquarters, Kessler takes an instant dislike to the newly arrived Luftwaffe Major Hans Dietrich Reinhardt, who has joined him in a final concerted attempt to crush the evasion lines. As the Allies continue to advance from the invasion beaches, Lifeline must continue their efforts in getting airmen back to Britain, but when Natalie attempts to guide two evaders down to Spain, it becomes clear that their work may at last be over.

An assassination attempt has been made on Hitler, and Kessler believes that Reinhardt is involved in the conspiracy. He begins to gather information that he hopes will provide his colleague’s guilt. Meanwhile, Albert becomes aware that the Communists are once more out to get Lifeline, and that he is their target.

Bradley travels to the Ardennes to continue recruiting his own private army of former airmen to engage in sabotage activities – the target is V2 testing sites. Bradley’s first objective, however, is to hijack a convoy of weapons and he asks Monique for assistance in recruiting men and resources. Lifeline, previously an evasion network, is now a fully-fledged guerrilla operation