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.

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?

The escape is on and there is tension in the air and not everything goes according to plan – but as some escapees find out, getting out of Colditz is only one part of the battle – getting out of Germany proves to be much more difficult.Flt-Lt Carter has been caught trying to escape but has managed to pass on valuable information which has made a previous escape plan possible. Captain Grant has been relieved of his duties as Escape Officer to lead them.

Mc Donald, a Scottish officer, receives a ""dear John"" letter and wants to escape desperately to put things right at home which puts the escape committee in a spot. Phil Carrington befriends the man and does what he can to help, but McDonald is tall and loud and stands out in a crowd – will anyone want to escape with him?

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.

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.

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.

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.

The opening episode takes place in June 1940. Captain Pat Grant (Edward Hardwicke) is captured and taken to a camp where he immediately starts organizing escape activity. After an unsuccessful escape he is sent to Colditz.

The bruised and unconscious body of submariner Lieutenant Dick Player is washed up on a beach somewhere in France. He is wearing plain clothes and speaks fluent German, which makes his captors believe he may be a spy. He escapes from the hospital where he is taken to recover but is recaptured and interviewed by the Gestapo. Player had once lived in Germany as the son of a diplomat and manages to get to speak to a childhood friend – now an important government official who offers Dick a chance to work with a plot to overthrow Hitler, but at a price.

The arrival of a new security officer – Haupman Ullman, leads to a tightening up of security. However the British contingent manages to eavesdrop on a meeting that will decide the strategic use of Colditz and they are surprised at what they learn. Meanwhile, the disillusioned German second in command (Michael Gough) is giving cause for concern with his behaviour, and when the Gestapo arrive, they spring a surprise on the Kommandant and his new security chief.

Action takes place in May 1940. After having a disagreement with his new wife, Flight Lieutenant Simon Carter (David McCallum) sets off for a night mission over Germany but he is forced to bail out of his crashing aircraft. On the ground, he befriends a young priest but the Gestapo arrests them both. Carter escapes first from the Gestapo and then from the prisoner of war camp he is assigned to – from there he is despatched to Colditz.

German guards are foiling too many escape attempts which leads Colonel Preston to believe that there is an informer working within the imprisoned population, so an inquiry is started to identify the suspect, but this sets off a chain of events which reveal the darker side of life in Colditz.

Colonel Preston receives bad news from home and has to make a decision about his command. Meanwhile Dick Player has to go to the dentist in town and gets set to escape, but while there he finds out information which could assist in a mass escape. It all depends on being able to bribe one of the guards, Private Heller – but will he play ball?

Colditz gets a new senior British officer, Colonel Preston (Jack Hedley). (The previous senior British officer, Major Donaldson is referred to in this episode but never seen). On his arrival he witnesses a futile escape attempt by Flight Lieutenant Carter and when the Kommandant meets him, he believes Preston is a man of honour who he can deal with. The colonel's new orders that seem to be appeasing the Germans cause conflict and dissension in the ranks, but there is method in the colonel's madness, which could come unstuck when a Polish officer decides to escape.

Wing Commander Marsh assists the British doctor as an orderly and he proposes escaping by feigning mental illness in order to be repatriated. The escape committee is not told of the plan and Marsh starts acting irrationally – however, the ever suspicious Ullmann appoints Private Hartwig to watch Marsh. Hartwig has a mentally disturbed brother and knows exactly what to look for. Will the wing commander be able to live the part and convince him?