Life on a British bomber base, and the surrounding towns, from the opening days of the Battle of Britain, to the arrival of the Americans, who join in the bomber offensive. The film centres around Pilot Officer Peter Penrose, fresh out of a training unit, who joins the squadron, and quickly discovers about life during war time. He falls for Iris, a young girl who lives at the local hotel, but he becomes disillusioned about marriage, when the squadron commander dies in a raid, and leaves his wife, the hotel manageress, with a young son to bring up. As the war progresses, Penross comes to terms that he has survived, while others have been killed.
