When German-born Louis Pfeif leaves home to join the Fifty-Eighth Illinois Infantry Regiment in 1862, his dog accompanies him. At Chicago's Camp Douglas, Bärchen charms Louis's fellow officers—even Colonel Lynch. As the Civil War escalates, the unit is transferred to Tennessee and placed under the command of General Lew Wallace. Shortly afterward, they come under fire at Erin Hollow. Bärchen proves his mettle—remaining by Louis's side amid the boom of cannon and the rattle of musketry. Then one morning the two are thrust onto a battlefield, where one will die and the other must learn to carry on.

Based on a true story and the history of the Fifty-Eighth Illinois, The Faithful Dog powerfully illustrates the unwavering bond of devotion between dogs and their humans.