In "Study in Pink," four people commit suicide by poison. When Holmes sets out to establish a link, he falls right into the culprit's clutches. Other cases concern a smuggling operation ("The Blind Banker") and a mad bomber ("The Great Game"). Though he doesn't make a formal entrance until episode 3, Sherlock's archenemy, Moriarty (Andrew Scott), has a hand in each mystery, while the detective's brother, Mycroft (co-creator Mark Gatiss), first appears when he tries to hire Watson as a spy, an offer the good doctor refuses. Through his job at a medical office, Watson also meets Sarah (Zoe Telford), who becomes his girlfriend.

Part of the fun of Jeremy Brett's Holmes (and Agatha Christie's Poirot) came from the period details, so this update takes a little getting used to--as does the occasional mumbled line--but Cumberbatch and Freeman share an enjoyable Odd Couple rapport, marked by flashes of deadpan wit, which compensates for the absence of deerstalker caps (Holmes favors scarves) and journals (Watson maintains a website). Extras include commentary on the finale, the original pilot, and a featurette, in which co-creator Steven Moffat (Doctor Who) notes that Cumberbatch was his only choice for the title role.