Flight Lieutenant Peter Howard, Captain John Clinton and Philip Rowe are Allied prisoners in
Stalag Luft III, a German prisoner of war camp in
World War II. Plans to dig an escape tunnel are complicated by the layout of the camp. Their barracks huts, the only place a tunnel entrance might be concealed, are a considerable distance from the
perimeter fence. To reduce the amount of digging needed, the prisoners come up with an ingenious way of shortening the tunnel. They decide to start the tunnel in the middle of an open area close to the perimeter fence and conceal the entrance with a
vaulting horse constructed from plywood from Canadian
Red Cross parcels. Recruiting fellow prisoners to form a team of vaulters, they carry the horse out to the same spot every day, with a man hidden inside. The prisoners
exercise using the vaulting horse while the concealed man digs underneath. At the end of the session the digger places wooden boards, cut to fit the aperture, in the hole and fills the space with sandbags and dry sand kept for the purpose since freshly dug sand would appear darker and give away the tunnel. As the tunnel lengthens, two men are hidden inside the horse while a larger group of men exercise and they recruit a third man, Phil, to assist them, with the promise that he will join the escape. When the tunnel is complete, Clinton hides in the tunnel during a roll call and Clinton and Phil are carried out in the horse with a third man to replace the tunnel trap and conceal the entrance again. They trio successfully escape and Howard and Clinton travel by train to the
Baltic port of
Lübeck. Phil elects to travel alone, posing as a
Norwegian margarine salesman and travelling by train via
Danzig. On the docks Howard and Clinton are forced to kill a German sentry who surprised the hiding men; and they contact French workers, through whom they meet "Sigmund", a
Danish resistance worker who smuggles them onto a Danish ship. They then transfer to a fishing boat and arrive in
Copenhagen before being shipped to neutral
Sweden where they are reunited with Phil who arrived earlier. ==Cast==