A World War 2 drama that highlights the characters (all aged only between 19 and 23 years) as much as the actual events. The British submarine Sea Tiger's crew is looking forward to a long shore-leave after months at sea. This is cut short when they are ordered to pursue and sink the German battleship Brandenburg. The crew's sub-Commander (John Mills) struggles to fulfil the mission despite discovering that the battleship is heavily defended. Along the way Sea Tiger encounters many obstacles and once the crew has attempted to sink the battleship they have to escape knowing that they are about to run out of fuel.