More than a spin-off of the Russell T. Davies incarnation of Doctor Who, the BBC series Torchwood is a wholly enjoyable blend of drama, science-fiction thrills, and mature subject matter that never fails to deliver its main purpose: to entertain on a weekly basis. John Barrowman, who captured the imagination of Who fans during the Christopher Eccleston and David Tennant eras as 51st-century adventurer Capt. Jack Harkness, returns as the dashing, immortal time traveler; here, he's the head of Torchwood, a covert organization that investigates extraterrestrial and supernatural events on Earth without the help of the British government or United Nations. Eve Myles is a police constable who joins the team after discovering them in the middle of bringing a stabbing victim back to life (in the debut episode, "Everything Changes"), and she brings a decidedly human touch to the Torchwood team's tech-driven investigations. Among the mysteries encountered over the course of the 13-episode series: an alien gas that absorbs humans during sex ("Day One"); a half-human, half-Cyberman female with a connection to Torchwood support man Ianto Jones (Gareth David-Lloyd) in "Cyberwoman"; a rash of cannibalistic murders ("Countrycide"); a very different kind of fairies than the ones of legend ("Small Worlds"); and most impressively of all, a skyscraper-sized demon that threatens to plunge the Torchwood team--and the world itself--into chaos ("End of Days," which features an off-screen cameo by a certain Time Lord). What separates Torchwood from the most modern television science fiction (save, say,

Heroes and Battlestar Galactica) is the frankly adult tone of the series: The violence is plentiful and occasionally graphic, and there are frequent bedroom couplings between the team members and supporting players. There's also a maturity to the relationships that exceeds the usual scope of sci-fi, most notably in the affecting "Captain Jack Harkness," which sends him back to the London Blitz, where he meets and falls in love with a handsome American pilot who happens to share his name. Their love affair, like the majority of Torchwood's "grown-up" storylines, is handled with taste and real emotion. Extras on the First Series are remarkably plentiful; six of the seven discs include entirely new behind-the-scenes featurettes that explore the main characters and their major story arcs, location shooting, the impressive SUV that the team drives, and the show's extensive special effects and alien creations. Barrowman also contributes a very funny "Captain's Log," which invites viewers to join him on one of the final shooting days of the series. The entire seventh disc is given over to Torchwood Declassified, the 13-part program which explored each episode on BBC Three and the BBC's Torchwood website. Commentaries are offered for all 13 episodes, with Davies, Barrowman, Myles, Burn Gorman (who plays Torchwood's medical officer, Owen Harper), David-Lloyd, producers Richard Stokes and Julie Gardner, and various episode writers, directors, and producers all lending their voices. A small battery of deleted scenes and outtakes, as well as previews for DVD releases of other BBC programs, including Doctor Who and MI-5, round out this impressive set. --Paul Gaita

Stills from Torchwood (click for larger image)