Lost deep in the enemy territory of the western front during World War I, allied soldier Private Charles Shakespeare (Jamie Bell) and eight other British soldiers from the Y Company seek refuge in maze of an abadoned German trench. Winding through the twisting tunnels through piles of corpses and hungry rats, the exhausted soldiers decide to hold thier position and await a rescue team. As the soldiers begin to fall prey to an unseen force, one by one thier numbers dwindle and thier suspicions of one another grow. A young soldier who illegally entered the armed forces at the tender age of sixteen, Private Shakespeare must now summon the courage to face an evil greater than he could ever imagine.