Jesse W. Haywood (Don Knotts) graduates from dental school in Philadelphia in 1870 and goes west to become a frontier dentist. Penelope "Bad Penny" Cushing (Barbara Rhoades) is offered a pardon if she will track down a ring of gun smugglers. She tricks Haywood into a sham marriage as a disguise. Haywood inadvertently becomes the legendary "Doc the Haywood" after he guns down "Arnold the Kid".