The X-Files: The Complete Fifth Season proves the show was -- even then -- still at its creative peak (if only for another year or so) and full of surprises. And many of them added significant twists to the show's mind-bending mythology. This is the year that gave us the cure for Dana Scully's mystery cancer, the fleeting appearance of her genetically engineered ''daughter,'' the origins of the Lone Gunmen, and the debut of Veronica Cartwright as a possible alien abductee whose relation to other major characters -- including the increasingly fascinating Cigarette-Smoking Man (William Davis) -- would make for some startling revelations in seasons to come.
Yet for all the intriguing new wrinkles in Chris Carter's series-long story arc, the revelation, on second viewing, is how many stand-alone episodes now look like classics. The most striking is ''The Post-Modern Prometheus,'' that tongue-in-cheek, black-and-white update of the Frankenstein theme. But for thrills and chills, there aren't many that have topped ''Detour,'' which finds Mulder (David Duchovny) and Scully (Gillian Anderson) being stalked by red-eyed, otherwise invisible predators in a Florida swamp. Like any ''X-Files'' season, this one had its clunkers -- most notably guest writer Stephen King's strangely uninspired tale of witchcraft, ''Chinga.''
But most of this set's filler can be found on its extra disc of ''bonus features.'' While devotees may enjoy hearing Carter discuss the technical difficulties of shooting ''The Post-Modern Prometheus,'' or watching Gillian Anderson giggle through a montage of blooper outtakes, the disc is overloaded with network promos masquerading as ''making of'' minidocumentaries -- none of which adds any insight about the series' many enigmas.
But then, ''The X-Files''' unsolved mysteries have always been a large part of its continuing allure, and in season 5, those mysteries were still getting deeper and darker -- even if the show's shadowy world would never again hold us so completely in its thrall.