"It's been a hard year for us," Aaron Hotchner (Thomas Gibson), leader of the FBI's Behavioral Analysis Unit, tells his mentor, profiler extraordinaire Jason Gideon (Mandy Patinkin) in the season finale. No kidding!  Just when you thinkCriminal Mindshas shown you the worst that humanity has to offer, the show unleashes an Emmy-worthy episode like "No Way Out," featuring Keith Carradine in a chilling performance as Frank, who just may be the most prolific serial killer in history, and whose capture in a desert diner is only the beginning of a battle of wits between himself and Gideon. From serial killers and a mad bomber to sadistic kidnappers and rapists, these are truly the cases that try men's (and women's) souls. In this second season, the writers have taken great care to flesh out the BAU team. In "The Aftermath," Elle Greenaway (Lola Glaudini), who still has not fully come to grips with being shot, steps over the line in stopping a serial rapist. In "Revelations," we see flashbacks to resident genius Reid's (Matthew Gray Gubler) painful childhood after a religious zealot (a scarily convincing James "Dawson" Van Der Beek), kidnaps, tortures, and drugs him (a later episode deals with Reid's addiction). In "Profiler, Profiled," devastating secrets about Derek Morgan (Shemar Moore) are revealed after he is arrested during a visit home on suspicion of being a serial killer.New to the team this season (following Glaudini's departure from the series) is Paget Brewster (perhaps best known as Chandler's short-lived girlfriend Kathy onFriends) as Emily Prentiss, an ambassador's daughter. "Welcome to our nightmares," she is greeted. Her addition allows viewers to see familiar characters fresh through her eyes.Criminal Mindsis potent stuff. "It gets to you," a character states at one point. Which might explain the gag reel clip in which Patinkin playfully breaks character during a scene in a playground by insisting on taking a spin on a merry go round and leaping on a teeter-totter (Patinkin would announce during the summer hiatus that he would not be returning to the show for season 3). Another fun extra, in addition to four illuminating episode commentaries and behind-the-scenes segments, is a profile of Kristen Vangsness, who portraysCriminal Minds' liveliest and most colorful character, "tech kitten" Garcia. Perhaps the only thing a newcomer to the series needs to know is that the term "unsub" means "unknown suspect." Its frequent use in each epsiode has the makings of a drinking game.--Donald Liebenson