During the middle years of the war, three men are called up to serve in the British Army. The Englishman Philip Hamilton (Underdown), the American David Morgan (Clanton) and the Irishman Smoke O'Connor (Michael Brennan (actor)) are conscripted into the Guards Division and report to their barracks at Caterham, Surrey. After going through strict training (including real Coldstream Guards Regimental Sergeant Major Ronald Brittain) they find themselves receiving emergency promotions. Philip and David are promoted to 2nd lieutenant and Smoke to corporal and are attached to a tank company of the Welsh Guards, where Philip and David command their own tank and Smoke is part of David's crew. Months of 'real' training follow, where they learn about tank warfare and also their comrades.