Tombstone, Arizona, 1881. The air is filled with the sounds of shooting, cussing, and toe-tapping tunes knocked out on the battered piano at the Last Chance Saloon. And then there is something less familiar: the wheezing, groaning sound of a Police Box materializing. The Doctor and his companions aren't the only newcomers in town. The Clanton brothers have ridden in to settle a grudge with Doc Holliday, the notorious gambler, drinker, and dentist. In the Wild West, tempers are short, guns are swift, and a moment's hesitation on the draw can mean death.