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?

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.

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.

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.