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.

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.

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.

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.

Major Nick Bradley returns to Brussels to co-ordinate resistance activities whilst waiting for the Allies’ final push, and clashes with Monique over leadership of Lifeline. A tense time is in store for Lifeline when Alain is arrested, and Bradley decides to make a deal with a German officer to try to get him out of Gestapo headquarters. However, the officer demands one million francs in exchange for Alain’s freedom.

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

As Bradley’s army remains in hiding along the Dutch border, he and Natalie become closer as they work together planning the raid on the V2 site. To increase his chances of success, Bradley must try to obtain the rocket delivery schedule and plans to get the information by dining with Kessler at the Candide…. Meanwhile, Reinhardt is rapidly closing in on Lifeline, with Natalie as his chief suspect.

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.

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.

Vercors has taken Albert, Monique and Reinhardt prisoner, and plans to hang Albert as a collaborator and a murderer. Only the Allies, helped by Natalie, can save him but they have only just entered Brussels. Meanwhile, Kessler and Madeleine are trekking on foot towards Germany through the Belgian countryside. To evade capture by the Allies, Kessler decides to take on a new identity.

The Allied liberation of Brussels paradoxically brings terror for the former Lifeline workers. About to face savage punishment after being falsely accused of collaboration, Monique is rescued thanks to Natalie and a British officer, Captain Stephen Durnford. She moves in with Natalie, where Durnford visits her and the two become close. Natalie tries to persuade Albert to declare his feelings for Monique, but he remains convinced that she will come back to him and the Candide. Meanwhile, Hans Van Broecken has to deal with two German deserters who have stowed away aboard his barge.

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.