Hoping to rescue a thoroughbred race horse named Dalleyrand from its trainer, Samantha transforms the horse into a woman named Dolly (Patty Regan). This proves to be a troublesome spell when the humanized Dolly begins giving "inside" race tips to Darrin's friend, Gus Walters (Robert Sorrells), who desperately needs money to finance a new invention. Sid Clute rounds out the supporting cast as trainer Jack Spindler. First shown on March 3, 1966, "The Horse's Mouth" was written by Paul David and John L. Greene.
by Hal Erickson synopsis