During a December 1944 German offensive in Belgium, a USO symphonic orchestra entertaining the front-line American troops is captured by the Germans. Initially, the Germans want to execute them, in accordance with orders received from Berlin. However, the orchestra leader, world-famous conductor Lionel Evans, persuades the Germans to spare their lives, arguing that his orchestra members are just civilian non combatants. Taken to the HQ of a German tank division, Lionel Evans and his orchestra members meet the German commanding officer, General Schiller, an avid music lover. General Schiller has respect for the musicians and he's hesitating about the standing order of executing all prisoners. However, the general's second-in-command, Colonel Arndt, is a blood-thirsty, by-the-book, type of fanatical officer who wants the prisoners shot. The general requests that Evans and his orchestra perform one more time, for him personally. Evans, out of pride and patriotism, refuses. But some members of his orchestra feel that performing for the General would keep them alive. A battle of wills between the General and conductor Evans ensues. The prisoners are kept in a castle's chapel, near the division's HQ. In the following days, the prisoners are fed and are allowed to practice their music in the chapel. When an orchestra member panics and tries to run, the German guards kill him. This prompts Evans to agree to perform one last concert for the German general and his officers. In the meantime, 2 American soldiers who had hid among the musicians before their capture, continue to pretend to be musicians, despite suspicions from the part of Colonel Arndt. Evans secretly agrees to allow the 2 soldiers to escape and seek help from the nearest Allied troops. During the escape attempt, one soldier is caught and shot. The other, is found dead in a field by the Belgian resistance. As the day of the concert approaches, one Belgian resistance member, posing as a local peasant, contacts Evans to tell him that an upcoming resistance attack will try to free the orchestra. The resistance attack would coincide with the concert for the Germans. General Schiller's tank division receives fuel and orders to join the offensive. Schiller orders his division out, while he remains behind for the concert. However, Colonel Arndt and a few men also remain behind to dig a mass grave in the castle's courtyard and to prepare the execution, after the concert. Tension builds up as the orchestra members, dressed in their official concert attire, file past the mass grave, to the chapel where the concert is to be performed. Conductor Evans wonders whether General Schiller will really have them executed or freed. Evans also wonders if the Belgian resistance attack will come in time to save them.