In 1943, the RAF Bomber Offensive against Nazi Germany is at its height. Night after night, the young crews of the Lancasters of RAF Bomber Command fly some of the most dangerous missions of the entire war. Their chances of surviving their tour of duty - just one in three. Wing Commander Tim Mason (Dirk Bogarde) has flown 89 missions. He has just one more combat raid to fly before he is rotated to the safety of a desk job. But confidence in Mason is waning amongst his superior officers. They think he's no longer fit to carry on and ground him prematurely. Mason defies orders and takes off on one last dangerous raid. As he flies into the bursting shrapnel and web of searchlights over his target, Mason believes he is certain to face court martial on his return, but the outcome of his actions are very different to those he believes he faces.