Major Peter Garnett (Hugh Williams) leads a team of men on a secret mission to France. Hiding out in a Chateau they must avoid capture by the Nazis as they make their plans. Our heroes quickly realise they will need to find a way into the local German HQ and persuade a local collaborator to assist them. But they know the personal danger they face in ascertaining the strength of Nazi forces, freeing their imprisoned comrade and escaping before they are tracked down. Made im 1942, 'SECRET MISSION' was produced to boost public morale after three years of War.