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.

Andre De Beers, a Belgian fighter pilot, is taken prisoner by the Gestapo and forced to watch his brother being tortured to death. De Beers overpowers his guard and escapes from Gestapo headquarters, seeking refuge with his old friend Alain. Determined to exact vengeance, he begins a campaign of killing German soldiers. After Kessler orders the capture and shooting of twenty innocent people in retaliation, Albert orders Alain to kill De Beers to stop any more bloodshed, however Monique and Natalie come up with an alternative solution. Albert is forced to stamp his authority on the others to preserve Lifeline’s safety when he learns that they have taken matters into their own hands. Meanwhile, as Kessler begins to launch an innovative new scheme to police Brussels, a communiqué from Berlin has shocking news for Brandt while sudden German radio silence indicates that a significant turn in the war is about to occur. The date is 6 June 1944.

Kessler tries to help Brandt as he tries to cope by heavy drinking and flirting with Monique at the Candide. Alain is forced to hide two evaders on his farm when a neighbour finds a wounded German fighter pilot on his property. It transpires that the pilot is a decorated flying ace and his plane is on the German secret list, and London asks for Lifeline’s assistance in getting him to England as a prisoner of war. Meanwhile, as Max prepares to bring his plans for Lifeline into fruition, Natalie demands that Albert take action.

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.

The Germans are out to capture a group of evaders, believing them to be responsible for the murder of an officer. One pair of evaders manages to contact Lifeline, while the other two throw their lot in with the Communists. Francois is determined to prove his worth as a Lifeline guide to Albert and Natalie, and decides to co-ordinate the journey down the line for all the evaders, approaching the Communists to take responsibility for the airmen against Albert’s advice. Whilst visiting the Communists’ hideout, Francois meets Max, whose true loyalties have begun to emerge in force.

Lifeline must work overtime when a heavy storm downs several British planes on their way back from a bombing raid on Berlin. Natalie comes into contact with Major Nicholas Bradley, a British officer on a special assignment, who is uncooperative and highly critical of Lifeline’s security when he follows her all the way back to the Candide. It seems that Bradley’s concern is well founded, as an undercover Gestapo man is also tailing Natalie.

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.

Brandt receives a visit from his wife Erika, who asks him to let her and their children come to live with him in Brussels as it is becoming too dangerous to carry on living in Berlin with the increasing British air raids. Brandt tells Erika that his work in Brussels may soon be over, as he has successfully infiltrated Lifeline with an undercover agent. Word of this reaches the Candide, and Albert must face the grim possibility of killing all evaders currently in hiding to preserve the safety of the line. However, Max and Dr. Keldermans have an alternative plan to discover the identity of the infiltrator, but the scheme requires the assistance of Natalie’s uncle, Hans Van Broecken, who hates Albert and will not help Lifeline.

A British Wing Commander is badly burned after he has been shot down over Belgium. London wants him back urgently, but his facial injuries make it difficult for him to go down the line. He manages to get to Paris with Natalie as his guide, but Monique decides that if he is to avoid detection he must disguise himself as a woman for the rest of the journey. Meanwhile, Madeleine is ostracised for her relationship with Kessler, but finds a new friend in Monique. The Candide and its staff are targeted by terrorists for being collaborators, and Natalie and Max fear the worst when the Gestapo arrest Albert.

Hoping to boost Lifeline’s flagging funds and gain some independence from London, Albert and Monique concoct a plan to sell three valuable Rubens paintings, replacing the originals with forgeries. However, Kessler is also aware of the paintings’ existence and plans to acquire them for Germany, setting out to remove them from the convent near Antwerp where they are held. Meanwhile, two American evaders, impatient with Lifeline’s security checks, decide to strike out on their own and ambush the car that Kessler is travelling in. Totally unaware of the true identity of their hostage, the Americans and their captive impose themselves on Hans and Lena Van Broecken, demanding that they are taken to Switzerland on their barge. Lifeline must not only retrieve the paintings, but also ensure that no harm comes to Kessler, as horrifying reprisals by the Germans are at stake.

Christmas is approaching, and Lifeline finds itself having to play Saint Nicholas when a wounded Group Captain is discovered by a group of abandoned children fending for themselves, who are prepared to sell the officer in turn for food and presents. However, Albert fears that it could all be an elaborate trap set up by the Germans. Meanwhile, Brandt finds his loyalties to Germany divided after recent events and confides his worries to Kessler.

Dr. Keldermans visits the Candide with tragic news, and Albert must take decisive action if Lifeline is to continue. Meanwhile, Natalie has the difficult task of taking two eccentric Russian evaders down the line. Brandt dines with a high-ranking military acquaintance, Oberst von Elmendorff, who tries to recruit him in a military plot to assassinate Hitler, while Kessler invites Albert to a strange garden party.

Natalie’s new boyfriend, Francois, is keen to become involved in Lifeline, but Albert has doubts. Paul Vercors, the fanatical leader of a Communist cell in Brussels, wants to take over Lifeline, and tries to enlist the assistance of a colleague – Max. Meanwhile, the Communists continue their resistance activities and plant explosives on a railway line to derail a train. Unfortunately, the train’s passengers include Natalie and Francois, escorting evaders down the line.