A new second-in-command is appointed to Colditz, but Major Mohn – a distinguished and much decorated soldier is determined to continue fight the war inside Colditz and Simon Carter whose broken ankle is not mending is prepared to meet him head on, but a psychological battle between them has consequences for the Kommandant and Colonel Preston, who is forced to appoint a new escape officer.

Simon gets an idea to hide prisoners to effect a dummy escape which would then take pressure off any genuine escape, but Major Mohn is highly suspicious and starts to impose further restrictions on the prisoners and this impacts Simon's plan and puts the lives of 2 men in danger.

A pair of caught French escapers bring back information that would greatly aid any escape attempt and Simon starts to devise a way of communicating with London – but it depends on his wife Cathy being able to understand a complicated code. At the same time a new prisoner – Page – seems to be a bit vague on facts and there is suspicion that he may not be all he appears to be.

The town jail is being used as an overflow for Colditz prisoners and while Dick Player is there he observes an intake of three new prisoners – but these men are British commandos and Hitler has given instructions for all commandos to be shot. An escape plan is hatched using the best route – but Major Mohn is taking more than a passing interest in these commandos and has ideas of his own.

Dick Player comes up with an escape idea that would involve going through the disused theatre, but things do not go according to plan when it seems the French have the exact same idea. Mohn is still investigating the last British escape and he is beginning to get close to the truth – but can Simon Carter divert his suspicions in a psychological chess game?

The arrival of one of Britain's top fighter pilots - Squadron Leader Tony Shaw causes disagreements in the German staff as to how to handle such a specialist prisoner – but Shaw turns out to be more interested in studying English literature with fellow inmate James Porteous – however will Shaw settle down to a life of study while Simon Carter is badgering him to become the focal head of escapes?

Colditz has a choir and they are asked by the local pastor to sing in his church for the Easter service. Captain Vaillant sees this as a means of escaping in order to avoid being transferred to Poland with the rest of the French contingent. Meanwhile a secret radio is bringing news of the war to Colditz.

A new prisoner - Collins seems determined to buck the system by going things alone and this causes friction with Simon Carter – all the more so because he is a card shark and is causing gambling fever - especially with George Brent, and with a German guard, Kruger who he intends to use for his own means.

A trio of Americans arrive at Colditz to join the solitary US inmate, Jim Phipps – but his suspicions are aroused when he sees the newcomers getting access to American newspapers and better provisions and despite the fact that there is a familiar face, the British wonder if in fact they are housing a German trained fifth column.

For the first time gunfire can be heard near Colditz. Lieutenant Colonel Dodd is dozed up with the flu and Phil Carrington acts as senior American Officer and he – with Colonel Preston has to handle a crisis when the Germans plan on moving the promenenti prisoners from Colditz – and there is bad news for the kommandant as the SS take an interest in Colditz.

Even though the war is reaching a close with the sound of gunfire and bombing being heard, there are tensions in Colditz. The British prisoners become suspicious of Major Mohn's new attitude towards them and his trips to the town reveal problems that will cause him to make a big decision.

The allied armies get closer to Colditz and there is unrest when a death sentence is passed against one of the prisoners. Colonel Preston starts to mobilise the British in preparation for a possible revolt. The kommandant receives some terrible news – and a visit from the SS.

The prisoners can now see battle activity from the upper reaches of the castle, but there is strong SS resistance and Colditz comes under attack. Phil Carrington makes a break for American lines, but the situation is very confused and there are many obstacles to pass before Colditz can be truly liberated.