The book centers on a racist colonel, Wesley McCulloch, and his black pursuer, Troy Harmon.

The theft of a World War II–vintage Sten submachine gun and the plans for such also add to the mystery about what McCulloch is up to.

Before long, Harmon comes to the conclusion McCulloch has used a secret experimental time machine to try to change the outcome of the American Civil War, giving victory to the Confederacy through the introduction of the easily manufactured Sten gun.

McCulloch is killed during the struggle in the past and Harmon successfully prevents his plans of revitalising the Confederacy.

He uses McCulloch's fortune to fund the First Regiment of Massachusetts Coloured Volunteers, which went on to fight nobly in the civil war.