What might be television's smartest and most intriguing science-fiction series pushes forward with 22 episodes (on six discs, including bonus material) comprising the third season ofFringe. The first season of this Fox show introduced us to the members of the Fringe Division (an obscure wing of the FBI assigned to investigate all manner of supernatural phenomena), and the principal characters, Agent Olivia Dunham (Anna Torv), mad scientist Walter Bishop (John Noble), and Bishop's son Peter (Joshua Jackson). In season two, we learned of the existence of a parallel universe, and that Peter is not Walter's real son, but rather his doppelgänger, whom Walter kidnapped when his own, "prime universe" son died. This two-universe paradigm now takes center stage--in fact, for the first third of the season, odd-numbered episodes take place in the parallel universe, with even-numbered ones set in "our world" (the remaining episodes are mostly, but not exclusively, in the latter). The two universes are substantially similar, notwithstanding some quirky differences, with everyone having a counterpart in the opposite world. Olivia, referred to as "Fauxlivia," spends multiple episodes in the prime universe; meanwhile, in the parallel universe, Walter's far less benign opposite number ("Walternate," Peter's real father) is the secretary of defense, who schemes to get his son back and annihilate the prime universe in the process. Thus Walter's kidnapping gambit 25 years earlier caused an off-balance chain reaction that threatens both worlds, while Peter, the only one who has no doppelgänger, becomes the linchpin, sort of the Harry Potter of the series; not only is he alone capable of operating Walternate's "doomsday machine," but he's also unique in believing that the two universes can coexist, instead of wiping each other out.Portions ofFringetake place in the past as well as the future, a fact that, when added to the ping-ponging between the two universes, can make the series somewhat confusing and a bit tedious, especially for newcomers. Fortunately, the weird science that made earlier seasons so enjoyable is still around. There's an "ultrasonic music box" that kills anyone who opens it, a strange blue powder that melts the bones of anyone who inhales it, beetles that eat people from the inside out, a "molecular destabilizer," and a "negative matter ring." Various episodes feature a nut who tries to reanimate his girlfriend by retrieving her harvested organs from those who received them when she died, shapeshifters who bleed mercury, a poor fellow who can't stop reading other people's minds, William Bell (Leonard Nimoy), Walter's old partner and friend, who at one point occupies Olivia's mind… and Walter's not-infrequent consumption of LSD. Trippy? You bet. ButFringe, with bonus features including multiple featurettes, a couple of audio commentaries, and other bells and whistles, is well worth the investment.--Sam Graham