Holmes takes a vacation and visits his old friend Sir Henry Baskerville. His vacation ends when he suddenly finds himself in the middle of a double-murder mystery. Now he's got to find Professor Moriarty and the horse Silver Blaze before the great cup final horse race.
The wife of a candidate for Parliament is having an affair with the brother of her husband's rival. Her lover is running for election on a promise of building a railway that the community needs, but a wealthy landowner won't give permission for the railway to be built over his land. When the landowner is later found dead, suspicion falls on the adulterous candidate.
Sir Douglas Rolls is a highly respected defence lawyer of many years experience. Now in rapidly failing health, he is advised to retreat from the courtroom and pursue more pleasurable activities. But it is just at this point in his life that his great lost love a woman his own strong sense of duty led him to give up twenty years ago, and whom he still loves deeply walks into his chambers to ask that he defend her adulterous husband, now to stand trial for murder. Reluctantly agreeing to take on the case, Sir Douglas soon finds there is more to the story than meets the eye.