During the Mexican-American War of 1846-48, many Irish soldiers in the U.S. Army deserted to join their Catholic brothers fighting for Mexico. The Mexican Army assigned them to el Batallón de San Patricio—the Saint Patrick's Battalion. After the American victory, the deserters were rounded up, court-martialed and shot.Now the sons and grandsons of those Irishmen and their Mexican wives are avenging the executions by launching hit-and-run attacks across the border into Texas towns. Captain Mack Hawkins and his Kiowa-Comanche Scout Detachment are sent to the area to put a stop to the raids. The captain and his second-in-command, Lieutenant Ludlow Dooley, quickly discover that the mixture of Irish and Mexican blood produces ferocious and incredibly brave fighting men. It's a sure bet there'll be hell to pay before the last bullet is fired.