The Doctor gets a Stetson (and a gun!), and finds himself the reluctant Sheriff of a Western town under siege by a relentless cyborg, who goes by the name of the Gunslinger. But who is he and what does he want? The answer seems to lie with the mysterious, Kahler-Jex, an alien doctor (yes another one!) whose initial appearance is hiding a dark secret.
Elenco: Matt Smith , David Tennant , Arthur Darvill , Karen Gillan , Jenna Coleman , Peter Capaldi , Jodie Whittaker , Billie Piper , Mandip Gill , Bradley Walsh , Tosin Cole , Christopher Eccleston , Freema Agyeman , Catherine Tate , Pearl Mackie , Matt Lucas , John Bishop .