An intensely gripping thriller set in wartime France in the spring of 1940 as the BEF faces a massive German blitzkrieg. Scouting ahead of the main force, a British Matilda tank - affectionately named 'Bert' by its four-man crew - is attacked by dive bombers and the railway tunnel that provides a welcome refuge becomes a death trap when the bombing seals the entrance. The crew dig desperately to regain their freedom only to find, when they emerge two days later, that they are some forty miles behind the German advance....