A British girl (Victoria Shaw) broadcasting for the Germans as a double agent obtains codes and frequencies for the Allies.

A dishonorably discharged flier (James Franciscus) masquerades as a replacement pilot in order to fly one combat mission.

When Gallagher and a pilot who resents him are shot down over the North Sea, they're rescued and treated with surprising decency by a U-Boat commander -- but the Nazi turns out to have a sinister hidden motive.

Fighter pilot Harley Wilson wants to be accepted by his fellow airmen, but sometimes he tries too hard—-as when he accidentally shoots up Gallagher's B-17 while trying to down a German plane. 

On the way back from a bombing run over the Ruhr Valley, Gallagher's battle-damaged B-17 accidentally drops its bombs on Ste. Monique, France. 1st Lieutenant Parks, the bombardier, is interrogated. A single bomb falls in the village square, killing resistance leader Pierre Fecamp. Two American pilots hiding in Ste. Monique escape: Major Coefield from the 918th and Captain Pollard from the 511th Fighter Squadron. Pollard has fallen in love with Claudine, the woman who rescued them and the daughter of Fecamp. She has brought her son to England badly wounded from the bomb's explosion, and he may lose his leg. Claudine hates Gallagher and is going to kill him. She goes with him to the 918th Officers Club and sees the pilots get drunk. Meanwhile, in Ste. Monique, Hauptman Bergdorf says they will not bomb again because of the last mission, so now they can put in a German Radar Station. On the way to Wing HQ in Archbury, Claudine tries to kill Gallagher. General Marteen orders the 918th to bomb Ste. Monique that night. In Ste Monique, German soldiers kill Marcel Lenoir as he radios information to London.

Off the base, JayDee Jones is working up the nerve to go on his next mission. He gets Jan Warner to sneak him back on base. He gets spotted by Chapman who is stealing 3 45 pistols to sell. JayDee's older brother Frank talks to him and tells him to straighten up. JayDee says he has had enough, he wants out. Jones and Chapman make briefing at 04:30. On takeoff JayDee over-revs his B-17's engines, but they don't have enough speed to take off. His co-pilot tries to help but the plane crashes killing the bombardier and badly injuring the co-pilot who dies later. Frank covers for his brother and says it could be a maintenance problem. Colonel Hunter the Wing G-4 (Supply) comes to investigate. Chapman sells his pistols to an Englishman who gets caught. Captain Mason from CIC comes to investigate the stolen guns. Jones co-pilot dies. Chapman and JD talk, Chapman says him will back Jones up. Hunter and Gallagher interrogate JayDee Jones, Frank Jones and Chapman. Chapman backs Jones who still can not remember

The 918th is being chewed to pieces while attempting to bomb a target in Norway, so secret that even Joe Gallagher doesn't know what it is or why it's so important. In fact, in its latest try, the mission commander, Col. Christie, decides to abort and turn back only 4 minutes from the target after losing 8 out of 21 bombers, with 4 more heavily damaged, including his own. Infuriated by the excessive losses and secrecy surrounding the missions, Joe alienates his superiors when he aggressively defends Christie against a looming court martial. To the rescue, possibly, rides his father, Lt. General Gallagher, who is hellbent on getting his son his first general's star. But Joe is in no mood to discuss promotion with his friend and the reputation of the 918th teetering on the edge of oblivion.