Boredom has set in at 221 Baker Street, with Sherlock (Benedict Cumberbatch, The Last Enemy, War Horse, The Hobbit) jonesing for a meaty case and — in its absence — a cigarette. Only the arrival of Henry Knight (Russell Tovey, Little Dorrit), terrorized and desperately clinging to sanity, piques the consulting detective’s interest. A gigantic hound — part tourist attraction, part conspiracy theory, part demonic moor stalker — is legend around Baskerville, a top-secret military compound where, it’s rumored, chemical and biological weapons experiments are conducted on genetically engineered animals. And Henry Knight has just seen the hound’s footprints in the very location where it killed his father decades before. Sherlock gleefully sets off to track the demonic hound with John (Martin Freeman, The Office UK, The Hobbit) at his side and Mycroft’s access-granting government ID on hand to enter the high-security corridors of Baskerville. But he may have opened doors to a realm where deduction and reason have no place. Written by Sherlock series co-creator Mark Gatiss (Doctor Who), The Hounds of Baskerville offers thrills, chills, laughs, and an unsettling, unprecedented facet of our hero’s clinically controlled mind. (One episode; 90 minutes, TV-PG)