Keeper of the TrakenThe Keeper of Trakenwas the beginning of the end for Tom Baker's tenure as the venerable TV sci-fi hero Doctor Who. By the end of the next serial,Logopolis, Baker had been replaced by the Fifth Doctor, Peter Davidson (whose debut,Castrovalva, is also available on DVD, as isLogopolis; both, along withKeeper of Traken, can be found in a three-disc boxed set titledNew Beginnings). But fans got one more witty and suspenseful dose of Baker's Doctor with this story, which sends the Time Lord and companion Adric to the planet Traken, a peaceful haven ruled by the all-wise Keeper for a thousand years. The Keeper feels his reign is coming to an end, and with it, the rise of evil from within Traken's governing council itself. The Doctor, however, recognizes the presence of a old and familiar foe at the heart of the mystery--one he thought had been vanquished long ago.Well-played by the cast (especially Baker, who is given a wealth of amusing lines), and an excellent launching pad for new companion Nyssa (Sarah Sutton),The Keeper of Trakenis both a fine addition to the Baker canon and an enjoyable serial for new and oldWhofans alike. Extras on the single disc include commentary by Sutton, actors Matthew Waterhouse (Adric) and Anthony Ainley (Consul Tremas), and writer Johnny Byrne; a 30-minute documentary on the serial, which includes interviews with most of the cast and production team; a clip of Sutton on the BBC seriesSwap Shop; and a featurette on the true identity of the evil plaguing Traken. The by-now-standard photo gallery, text-only commentary track, and PDF of theDoctor Who Annual(here from 1982),Radio Timeslistings, and BBC sales literature rounds out the crowd-pleasing supplements.--Paul GaitaLogopolisAfter seven years as the Doctor on England's long-running science fiction seriesDoctor Who, actor Tom Baker hung up his scarf and retired from the role in this four-part serial from 1981. )(The second in a three-part story arc focused around the Doctor's longtime adversary The Master (Anthony Ainley), (The other parts of the arc,CastrovalvaandThe Keeper of Traken, are also available on DVD as single discs and in a three-disc set titledNew Beginnings)Logopolisfinds the Time Lord in a contemplative mood as he attempts to repair the TARDIS' broken chameleon circuit, which has left the shape-shifting vehicle in the form of a police box. The Doctor and Adric (Matthew Waterhouse) travel to Logopolis, a planet run by mathematical geniuses, but encounter the Master as he plots to steal the secret of the planet's massive radio telescope. His scheme accidentally releases a wave of entropy that threatens to destroy the universe, and the!   Doctor and the Master must work together to prevent the end of existence itself. A sense of finality pervadesLogopolis, and certainly for Baker fans, it does mark the end of the actor's run in the role, as well as a period of considerable popularity for the series. Baker's replacement, Peter Davidson, faced an uphill battle when he assumed the Doctor's mantle, and for many fans, his arrival signaled a downward turn for the program that was not reversed until its revival in 2005. The story itself is an intriguing one, and well played by its cast, which included newcomer Janet Fielding as airline stewardess Tegan Jovanka, who became one of the Doctor's companions for several seasons. Extras on the disc include commentary on all four episodes by Baker and Fielding, as well as writer Christopher Bidmead; a trio of BBC news program interviews with Baker on his departure and Davidson on his assumption of the role; a terrific 50-minute featurette titled "A New Body At Las!  t," which interviews many of the principal cast and crew on the transi tion from Baker to Davidson; and the usual PDF of printed material fromThe Doctor Who AnnualandRadio Times, as well as the excellent text-only commentary and isolated music tracks fans have come to expect from the discs.-- Paul GaitaCastrovalvaThe four-episode serialCastrovalvanot only kicked off the 19th season ofDoctor Who, but introduced the fifth incarnation of the venerable British sci-fi hero in the younger (and blonder) form of Peter Davidson, who replaced fan favorite Tom Baker at the end of the previous season. Castrovalva picks up where the Baker finale,Logopolis(also available on DVD), left off, with the Doctor in a weakened state after his transformation, and in need of rest and recuperation. His companions set a course for the planet of Castrovalva, but all is not as it seems on the peaceful and educated world: Could the Doctor's old nemesis The Master be setting a trap for the ailing Time Lord?  It's a strong debut for Davidson, who quickly sets his own path as the Doctor (while referencing his predecessor's traits and quirks in several clever bits), and the single disc DVD's extras do an excellent job of covering the transitional phase that the cast and crew underwent during the serial's production. Davidson is front and center on the commentary tracks for all four episodes, and he's joined by castmate Janet Fielding (Tegan), director Fiona Cumming, and writer Christopher H. Bidmead. And he's the focus of two featurettes: "Being Doctor Who," which covers his tenure as the Doctor, and "The Crowded TARDIS," in which he joins Baker, Fielding, and Sarah Sutton (Nyssa) to discuss the Doctor's multiple companions in the Davidson years. Cumming is also profiled in a short feature on directing the episode, and the BBC vaults yield interviews with Davidson from the period on the children's showsBlue PeterandSwap Shop. A pair of deleted scenes, continuity announcements, a photo gallery, the usual above-par text commentary, a PDF of printed material on the show, and a music video for a remix of Peter Howell's theme music round out the supplements.-- Paul Gaita