Soldier is a fanciful tale told by three border collies. The story begins in a time when America is engaged in civil war. "Soldier" as he will become known to the boys fighting for the Republic, shares their experiences on the battlefield. After Soldier's master is discharged from the Army, he travels west, eventually joining the glorious Seventh Cavalry, under the command of George Armstrong Custer. Soldier survives the Battle of the Little Bighorn, but his master, Paul Belleu, does not, leaving his pregnant wife, Mary Belleu, a widow. Thereafter, Mary moves on, experiencing many dangerous adventures in the American West. Eventually, Soldier and his mistress, Mary, end up on a ranch in Arizona, after some scary moments fighting the dreaded Apache. When the "keeper of the flame" (Soldier, the first) passes on, Soldier's son takes up the challenge of protecting Mary as they travel to New York City, then on to Ireland, Mary's birthplace. When Soldier, the second, passes the torch to his son, (Soldier, the third), he becomes the companion of Peter Forester, Mary's great-nephew and heir to the family fortune. Seeking adventure, Peter and Soldier set off for the goldfields of California, where a poor man could become a millionaire overnight. Together they do battle with mining companies that are squeezing out the original gold prospectors who want nothing more than to work their claims.