CSI CSI

CSI: Crime Scene Investigation
9/8c CBS
The buzz surrounding the 10th-season finale is that one or more of the CSIs won't live through the episode...but is that reality or just hype? Tonight, Catherine arranges to get serial murderer Nate Haskell (Bill Irwin) transferred to Las Vegas, against Brass' strong objection, after he claims to know the identity of the elusive serial killer Dr. Jekyll. This much is known: One CSI member is gunned down by Jekyll midway through the episode (but does he or she die?), and there is a major twist in the story. Regardless of what happens, it's a must-see finale for any CSI fan. — Tim Holland

Bones

8/7c Fox
You'd think Brennan would be glad that the Grave Digger isn't likely to harm anyone ever again — Heather Taffet's menacing "This isn't over" comment notwithstanding. But the good doctor seems to have other things on her mind, and they don't appear to be what she's been doing for the last five years. The future will have to wait, however, at least until this fifth-season finale sorts through a hoarder's many possessions to find the reason for his death. ZZ Top's Billy F. Gibbons guest stars. — Joe Friedrich

Grey's Anatomy
9/8c ABC
It's time to put the wraps on Season 6, and the hot docs had better watch out: Season-finale season can be dangerous to a series regular's health. Ask George. Oh, we can't: He was run over by a bus last year. Tonight, George's colleagues must deal with a shooter on the loose at Seattle Grace-Mercy West. But while they're dodging bullets, how about Cupid's arrows? Bailey-Ben seems to be holding up (for now), but will we say good-bye to Cristina-Owen? Is Calzona finally over, too? And as for Lexie: Alex or Mark, who'll it be? Mandy Moore guest stars. — Paul Droesch

Fringe
9/8c Fox
The minute we saw the cocky, auburn-haired Olivia from the Other Side, you just knew there would be a showdown with the more serious one from our world, didn't you? Well, place your bets, because it looks like we'll get a fight for the ages in the conclusion of the second-season finale. But there may be implications far greater when Walter comes face-to-face with William Bell (Leonard Nimoy), who seems to have been nursing a major grudge since his old colleague took Peter all those years ago. — Joe Friedrich

The Mentalist
10/9c CBS
When Patrick Jane met psychic Kristina Frye (Leslie Hope), it didn't  require Jane's skills to see that there were romantic sparks...and that they would meet again. Their reunion in the last few episodes has been one of the best things about this second season, and in the season finale, they go on their first date. Unfortunately, it ends too soon when a murderer copying Red John's MO strikes. The case not only ends their date abruptly, but threatens to cut their lives short as well. — Bill Ecklund

The Office
9/8c NBC
A well-spun Season 6 closes on Michael Scott and his desk jockeys. Through the year we witnessed Sabre rattling and buying out the office, Jim and Pam having their baby, Andy and Erin building a romance and Michael wooing a hot-spot barmaid, and it all crescendos with a decidedly fiery finale. The pressure is on when the press learns that Sabre's printers catch on fire, sparking office tension and the arrival of Sabre CEO Jo Bennett (Kathy Bates). With blazing intent, Bennett is determined to smoke out the whistle-blower. The staffers point accusatory fingers at Andy, who passionately denies that he's the leak. — Dean Maurer

30 Rock
9:30/8:30c NBC
Wedding bells blare in the sharp ensemble sitcom's guest-packed Season 4 finale. Liz is in an "altar"-ed state: She must deal with three different nuptials when Floyd (Jason Sudeikis), Cerie and Grizz all get married, but Liz still manages to meet her Mr. Right Now. Elsewhere, Jack's wild love triangle with well-pampered Avery (Elizabeth Banks) and crush Nancy (Julianne Moore) reaches a crucial point. And Kenneth tries to avoid a promotion that would send him to Los Angeles. Matt Damon, Will Forte and Michael Sheen also guest star. — Dean Maurer