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.

Albert is finally released from prison and reunited with Monique. The Lifeline personnel continue to be in danger of reprisals from their own people and the Communists for alleged collaboration with the Germans, but Albert refuses to leave the Candide. The Allies are still making their way towards Brussels, and Natalie and Alain join the offensive. As Kessler and his men leave the city, Reinhardt stays behind to complete his investigation into Lifeline and pays one last visit to the Candide, just as Paul Vercors emerges to take ultimate revenge on Albert.

The Allied advance continues as they at last enter Belgium, and the Germans begin to plan a strategic withdrawal from Brussels. Albert is petitioning for his release from prison, while Bradley endeavours to forge links with other resistance groups. The people of Brussels are now left to their own devices, and recriminations are brewing for collaborators and black marketeers. Kessler comes to help Madeleine, while Alain offers Monique and Natalie a place to hide. Meanwhile, Reinhardt at last obtains proof that the Candide is Lifeline’s base of operations, and prepares to strike.

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.

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.

Curtis’ cover has been blown and Kessler knows that he is part of the resistance. To avoid endangering the others, Curtis goes to ground in Brussels. Knowing that Lifeline is at last in his sights, Kessler orders that all routes out of the city are blocked and co-ordinates a house-to-house search throughout the city. In desperation, Curtis goes to the Candide to ask for help, and Monique comes up with a highly audacious escape plan.

Lifeline’s original function is now over – the Allied advance has severed the evasion lines and it is now a matter of keeping evaders safely hidden until the war is over. Despite Kessler’s irritation at Reinhardt’s manner and methods, his efforts pay dividends when he discovers a Lifeline safehouse. Two of his new prisoners commit suicide rather than talk, but Reinhardt is determined that the third prisoner will give information under torture. Albert and Monique receive a tip-off that the middle-aged Chantal sisters, who are based in Senlis and often shelter airmen for Lifeline, are in imminent danger.

The safety of Lifeline is at risk when Albert deduces that the Candide is being watched by a Gestapo spy, while Lisa continues to resent Curtis’ presence and his domineering take-charge manner. A wounded RAF evader, Finch, finds sanctuary with Hans Van Broecken, a Dutchman who lives on a barge with his wife Lena. Finch plans to desert the army and escape to Switzerland and finds a kindred spirit in Hans, who is in fact German and deserted during the First World War. Hans plans to take Finch to Switzerland himself on the barge, but Lifeline becomes involved when Lena receives a visit from her niece – Natalie. However, helping evaders escape to comfortable Swiss internment is not Lifeline’s purpose, and how can Finch be involved with Lifeline with the Candide under German surveillance?

An American airman has written a magazine article about his experiences being shot down in Europe and getting back home with the help of the evasion lines. British Intelligence has blocked the article’s publication, but Brandt has managed to obtain a copy from German intelligence based in America. Studying the article, he begins to deduce the probable route taken during the evasion and travels to the Pyrenees, where he enlists the aid of Malaud, a French policeman, to close in on the line. Meanwhile, Lisa is also in the area, taking some evaders down the very route Brandt is so close to tracking down.

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.

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.

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.

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.

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.

Albert is imprisoned on trumped-up charges as part of a Communist revenge plot, and Monique is left to take charge of both Lifeline and the Candide. Alain discovers the existence of a false escape line set up by Reinhardt to flush them out and that one of their evaders, “Mad” Mike Miller, had previously been shot down and helped by Lifeline. Monique must make a difficult decision if she is to maintain Lifeline’s safety.

A British bomber crash lands somewhere outside Brussels, its entire crew is apparently dead. Kessler takes this as an opportunity to infiltrate Lifeline and assigns Ernst Stoller, an officer who was born and brought up in England, to substitute for one of the dead men. Meanwhile, Monique is becoming increasingly disillusioned with her life at the Candide and relationship with Albert, and finds herself letting her guard down when she becomes involved with Stoller as part of her Lifeline work.

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.

Kessler, still posing under an alias, and Reinhardt find themselves interned in the same prison camp for German officers. Kessler learns that Reinhardt surrendered himself to Albert at the Candide and is determined to dispose of him with a trumped-up court martial. Madeleine is forced to make a decision that will change her life forever. In Brussels, Albert and the others learn they are to be decorated for their selfless contribution to the war effort and Albert is given full ownership of the Candide as a reward for his bravery. However, it is a bittersweet victory for Albert as he has lost Monique, who is about to marry Captain Durnford and leave for a new life in England. The Second World War is over.

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.

The Jewish population of Brussels is being systemically deported according to colour-coded identification papers developed by the Germans. Curtis becomes involved with a Jewish family hiding out in the city and asks Lisa if Lifeline can help, but Lisa is unwilling to put the line, which is supposed to help RAF evaders not Jews, at risk. Curtis himself is still under suspicion by Albert, when Lisa’s uncle, bank manager Gaston Colbert, identifies Belgian banknotes he brought over from London as forgeries. Kessler obtains some of the notes, and realises that they are too accurate to be real and have been made by the Belgian treasury plates, which were evacuated to London before the German invasion. He believes that the notes will bring him closer to Lifeline.

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.

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.

Still languishing in prison, Albert learns that he was set up by the Communist leader Paul Vercors. Meanwhile, Dr. Keldermans makes a shocking discovery when examining an evader at a safehouse – the man is dying of bubonic plague. Lifeline’s personnel face the horrifying possibility of being wiped out by the deadly disease.

With so many evaders, Lifeline’s resources are once more stretched to the limit and they must watch their backs after recent events. Jacques and Natalie are dispatched to check out a young South African evader, Noel Uys, and have to consider eliminating him when his answers to their questions fail to satisfy either them or London. In desperation to survive, Uys overpowers Jacques and armed with a shotgun, takes Natalie as his hostage.

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.

When Lisa Colbert is arrested whilst meeting a contact near Paris, the whole future of Lifeline is put at risk. This also leads to her uncle being arrested and interrogated by Kessler. Whilst in prison, Lisa must decide whether she can trust her fellow inmates who claim to know who she is and how they can help her escape. These events will lead to tragedy, both personal and for Lifeline.