Legends of autumn

Sick of betrayals the United States government perpetrated on Native Americans, Colonel William Ludlow leaves the Army, moving to a remote part of Montana. Along with One Stab, a Cree friend, he builds a ranch and raises his family. Accompanying them are hired hand and former outlaw Decker, Decker's Cree wife Pet, and daughter Isabel Two. William has three sons: Alfred, the eldest; Tristan, the middle son; and Samuel, the youngest.

The brothers find themselves in the 10th Battalion, CEF. Alfred, commissioned as an officer, leads a charge into no man's land. The attack results in heavy casualties and Alfred is wounded. While visiting Alfred in the field hospital, Tristan learns that Samuel volunteered for a dangerous reconnaissance mission. He rushes off to protect his brother but arrives too late. Tristan holds Samuel until he dies, then cuts out his brother's heart and sends it home to be buried at the ranch. Tristan single-handedly raids the German lines and returns to camp with the scalps of German soldiers hanging around his neck, horrifying his fellow soldiers. He is discharged but does not go home. Alfred returns to Montana and proposes to Susannah, but she declines.

Years later, Samuel returns from Harvard University with his fiancée, Susannah. Susannah finds Tristan captivating but loves Samuel. Before they can marry, Samuel announces his intention to join the Canadian Expeditionary Force and aid Britain in the fight against Germany. Much to their father's displeasure, Alfred also joins. Although Tristan does not want to join, he does so after swearing to Susannah to protect Samuel.