It is three weeks after the escape and there has been a shake up at Colditz.
A new second in command has arrived. He is Major Horst Mohn of the SS, and he is out to make as much trouble as possible. He takes a dislike to Simon Carter mainly because he is jealous of Carter's loving relationship with his wife Cathy.
Simon Carter is the new Escape Officer. He gets the idea of concealing men in Colditz as 'ghosts' in order to confuse the Germans about exactly how many men are in the castle at the one time.
The first hiding place is under the pulpit in the Chapel at Colditz and the first two volunteers to be 'ghosts' are Dick Player and George Brent. Unfortunately the French are building a tunnel under the Chapel which is discovered by the Germans. The Chapel is sealed up, and Player and Brent are trapped.
Carter sets up a system whereby he can communicate with his wife Cathy using coded messages.
A new prisoner arrives in Colditz. He is extremely violent, and the men believe that he may be a German spy. Carter advises the men to leave this man alone.
Three British Commandos have been captured in Germany. Unfortunately for them, Hitler has given orders that all Commandos are to be shot.
Lieutenant Colonel Preston does his best to save the men. He requests that they be brought to Colditz Castle from Colditz Gaol, and an effort is made to make it look as though the Commandos have escaped from the Castle.
Player and Walsh devise a means of escape using a room at the back of the theatre in Colditz. Unfortunately a couple of French prisoners have a similar idea and the escape plan is temporarily suspended.
Major Mohn engages in a game of chess with Captain Simon Carter, and reveals that he is aware of the prisoner substitution scheme whereby two officers hid on a rotational basis within the confines of Colditz thus confusing the nature of the exact number of British prisoners held there.
Squadron Leader Shaw is a war hero, and when he is captured and brought to Colditz he becomes the most highly decorated man in the Castle.
However, despite Simon's urgings he does not seem to be interested in any form of escape, preferring instead to lead a solitary life reading and teaching English literature with the Camp's other schoolmaster, Captain James Porteous.
However, given time to reflect, Shaw comes to know himself and to realise that he revels in his hero status and craves the admiration of his fellow man. He eventually proposes the most original and audacious plan of escape ever put forward by any prisoner.
It is Easter, 1943 and the local pastor from the town of Colditz asks the Kommandant if some of the prisoners will sing in the Protestant Church in Colditz town for the Easter celebrations. The British give their word that they will not attempt to escape, but a Frenchman attaches himself to the Group and later makes a successful escape bid.
Collins is a new prisoner at Colditz, and is a card sharp and cheat. He causes a great deal of conflict within Colditz and one man even loses his life because of him.
Major Mohn temporarily loses control of the prisoners. It is left to the Kommandant and Lieutenant Colonel Preston to restore order.
Three very senior American officers are captured and brought to Colditz. One of them is Major Carrington who had earlier made a successful escape from the castle.
It is the spring of 1945 and the war is drawing to its conclusion. Hitler has ordered that all politically expedient prisoners, known as 'the prominente', are to be taken to a separate camp.
The Allies, along with the Kommandant and other German Officers at Colditz try to resist this order, but the SS over-run the castle and threaten to take hostages.
Carrington is arrested and faces a court-martial.
Major Horst Mohn is panicking as he sees that Germany is losing the war. After several attempts at ingratiating himself with the British prisoners he takes matters into his own hands.
Carrington has been sentenced to death. All is confusion at Colditz as communications have broken down. The Kommandant's wife moves into the castle where she is safe from the advancing Russian troops. Shaw's plans with the glider which he has been building for the past ten months have to be shelved for the time being, as the Kommandant warns Colonel Preston that any attempts at escape by the prisoners will give the SS an excuse to relieve him of his position as Kommandant at Colditz Castle. The Kommandant also receives some dreadful news.
He informs Colonel Preston that Colditz is to be evacuated.
The war slowly comes to an end, with the allied prisoners and the Germans gradually forming a united front against threats from the advancing Russian army and the SS. The castle is bombed by allied forces who are not aware of its true nature, and all the inhabitants gather together in the cellars with this threat drawing them closer together.
Ultimately the Americans free Colditz, and the Kommandant surrenders to them. He and Colonel Preston realise that nobody has won anything out of the war.