On a September morning in 1916, a handful of lumbering steel machines crawled across the mud of the Somme and changed the way armies fight. Guy Martin, better known for tinkering with motorbikes, sets out to understand how Britain's first tanks were designed, built, and thrown into combat with almost no testing and crews who had no idea what they were getting into. He gets hands-on with the mechanics, examining the cramped, scorching interiors, the unreliable engines, and the primitive steering that made early tank crews as much at war with their own machines as with the enemy. Historians and archival material fill in the wider picture: the secrecy around the project, the skepticism from generals who doubted armored vehicles could work at all, and the chaotic first outing at Flers-Courcelette. The film treats the tank not as an inevitable triumph but as a desperate, improvised gamble that happened to work, and traces how that gamble reshaped land warfare for the rest of the century.