Professor Moriarty is determined to ruin the outcome of the Barchester Cup by stealing Silver Blaze and murdering the horse's trainer. Sherlock Holmes senses his old nemesis at work, and traces a twisting path of clues to find the animal and return him to the track. After learning that the horse has been recovered by his arch-enemy, Moriarty responds with a rage that could only be quelled with blood. A henchman is sent to dispose of the detective, and Watson is taken prisoner, before the rivalry between the two foes reaches a chilling climax at the Baskerville estate. Regarded as one of the most faithful adaptations of the work of Sir Arthur Conan Doyle, Murder at the Baskervilles develops the original story by drawing on the familiar characters of Professor Moriarty and Inspector Lestrade. Originally released in Britain as Silver Blaze, it was Wontner's last appearance as Holmes before Basil Rathbone took over the role.

This early Holmes mystery centers around the theft of a racehorse, "The Silver Blaze."