Stubby, a Boston terrier, is scrounging for food in the streets of New Haven, Connecticut, in 1917 when he is adopted as a mascot by the 102nd Infantry Regiment and finds himself on the way to France and the trenches of World War I where he soon learns to save his soldiers by alerting them to impending gas attacks, and eventually is awarded a medal by General Pershing.

Based on the story of a real dog in World War I, and told from the dog's point of view.