December 1915. Following heavy casualties, General Townsend withdraws his exhausted troops to the town of Kut Al Amara, Iraq. His orders - to engage as many Turkish troops as possible in a siege situation.

A relief force is hastily assembled, among them Charles Reid, Tom Mason, and Michael Downe, for each of whom the advance is personal. Charles returns to the country where he lost the love of his life. Tom's brother John, an army surgeon, awaits execution. Michael's brother Harry, an army intelligence officer, is missing, having never returned from his last mission.

Short of everything except the sick and wounded, reduced to eating their horses, the column is repeatedly thrown against the might of the Turkish guns as they wonder if they will ever see home and their wives again. For the women in their lives, the strain reaches breaking point as they wait for news from the front.

As the death toll rises, the British War Office faces the unthinkable: defeat for Townsend and his 10,000 men.