The Great Game

The first two cases let Sherlock be clever. This one finds his equal. An anonymous mastermind begins setting timed puzzles and bomb threats across London, and each one arrives with a countdown attached. A strange clue in an empty room. A blood-soaked car. A priceless Old Master. A deranged bomber. Get it wrong, and someone dies on the mastermind's schedule. The countdowns are short and the choices are ugly, and Holmes, for once, is playing someone else's rules.

The stranger seems to know all the answers before the questions are asked, which unsettles Holmes in a way the puzzles themselves don't. Watson races along beside him, and the episode is smart about using John as the audience's tether: he's the one who keeps asking what the point is, while Holmes is busy admiring the game. Each challenge is a self-contained story, which lets the hour skip between settings and moods without losing momentum, and the fear has time to build because the mastermind never appears, only a voice on the phone and other people's bombs.

The show saves its best card for the end. The name on the case is Jim Moriarty, played by Andrew Scott, and the reveal changes the temperature of the whole show. From that phone call on, Sherlock stops being a detective story with a genius in it and becomes a duel. It is the episode that takes the series from clever to dangerous. Mark Gatiss, Steven Moffat and Arthur Conan Doyle wrote it, Paul McGuigan directed, and around the two leads are Rupert Graves as DI Lestrade, Una Stubbs as Mrs Hudson, Zoe Telford as Sarah, Louise Brealey as Molly Hooper, Vinette Robinson as Sgt Sally Donovan, Matthew Needham as Bezza and Kemal Sylvester as the Tube Guard.

The game, as the show would say, is on. And from here on, it never quite lets up.