A lone British tank crew finds themselves isolated behind enemy lines during the desperate retreat to Dunkirk in 1940. Sergeant Barnes, Corporal Penn, and Trooper Reynolds operate a Matilda tank named Bert, tasked with navigating a landscape overrun by the advancing 14th Panzer division. Their objective is to survive and disrupt the German advance, despite being vastly outnumbered and lacking support. The narrative follows their high-stakes movement through occupied territory, emphasizing the claustrophobic conditions of tank warfare and the tactical ingenuity required to survive against superior forces.

This novel is recognized as a quintessential example of the high-tension military thriller genre from the late 1960s. The premise suggests a focus on technical detail and the visceral reality of armored combat, which aligns with the author's reputation for meticulous research. Readers likely appreciate the claustrophobic intensity of the narrative, which effectively captures the desperation of the early stages of the Second World War. The story functions as a character study of men under extreme pressure, highlighting the contrast between individual bravery and the overwhelming scale of mechanized warfare.