The beauties and geeks travel to Las Vegas and compete in an unconventional game of strip poker. Once exposed, the geek's test their new-found social skills by throwing a party only Vegas could handle. Once everyone returns to the house, an unlikely crush grows between a beauty and a geek, while in the elimination room, two teams face questioning and one is sent packing.

While Chris develops a crush, Julius and Rochelle have their work cut out dealing with all of Tonya's and Drew's admirers.

Earl is nervous about returning a laptop computer he stole from a college professor, mostly because he is uncomfortable around smart people. When the professor turns out to be a beautiful woman, he feels even more ill at ease, until she flatters him and asks him to speak about his list in front of her class. Meanwhile, Randy experiences fraternity life and absolutely loves it.

Chloe is possessed by the spirit of a young girl whose body is sealed in the Talon's walls, and goes searching for the girl's killer while Clark and Lois try to track her down.

The Older Men tribe struggle at their camp through a rough storm and Shane begins to have second thoughts as to why he's playing the game. When the 4 tribes become 2, new alliances take shape. After winning a reward challenge, Sally tries her hand at fishing and loses the fishing spear. In the end, Casaya loses the Immunity Challenge and votes one of their own out.

Red lets Hyde in on a Valentine's Day secret, Christine opens up to Jackie about her love life, and Randy has big plans for a date.

The dance-off heats up when each couple performs twice.

A second group of celebrities are paired with professionals in a ballroom-dance competition. The hoofer hopefuls include:

* Jerry Rice
* Lisa Rinna
* George Hamilton
* Stacy Keibler
* Drew Lachey

The CSIs investigate the gruesome murder of Lady Heather's estranged daughter, Zoe, who was found in the middle of the Vegas desert.

Whilst at a wedding, Carter witnesses the first in a chain of deaths that confuse the Deviant Crime Unit and the bomb squad. As little evidence for the cause of deaths is left at the scenes of the crimes, both departments are stuck for answers. There is a twist when Jack and Carter soon discover that everything was not as it originally seemed.

A tragic event takes its toll on the community, Kaitlin prepares to go back to school, Ryan questions his relationship with Marissa after lending a helping hand to Sadie, and Kirsten and Julie decide to go ahead with a Valentine's Day party.

The Dunder Mifflin staffers join in kindergarten-like festivities for Valentine's Day while Michael heads to New York City for a conference with the corporate heads. Pam becomes irked when she discovers that Roy hasn't gotten her anything for Valentine's Day, Dwight struggles to find a gift for Angela, and Kelly talks off Jim's ear about her rather desperate affections for Ryan, who is less than interested.

The big day has finally arrived as Grace and James get ready for their green-card wedding. To Grace's dismay, Karen takes it upon herself to ignore her wish for a low-key wedding ceremony and decides to arrange a huge affair instead including hiring the legendary Hall & Oates singing duo to perform 'Maneater' at the ceremony. As the ceremony gets underway, it seems that Grace's body begins to have an unusual reaction leaving James' U.S. citizenship in jeopardy.

An unexpected visitor puts Clemente in the middle of a domestic dispute, and things dont look good. As the police sort out events, Luka, Abby and Sam try to save the victim in the aftermath of a shooting. Luka and Abby await important news about the baby. Pratt finds himself the center of unexpected attention at a fundraising event.

When Leah Robinson goes missing after a confrontation with a young man at an art gallery, the team mvoes in to investigate and soon become suspicious of Leah, suspecting her of murdering young women that she believed to be involved with her husband, Ken. Ann isn't quite ready to take her romance with Jack public, and their relationship gets rocky when their different methods of handling the case tip off the suspect.

TONIGHT: Actor and star of Arrested Development, Will Arnett!

TONIGHT: Stephen Colbert welcomes the author of The Assassins' Gate: America in Iraq, George Packer!

Love is in the air with the IT Crowd! Roy has a wonderful date, only to learn that he had something nasty on his forehead the whole time. Jen fancies the security guard and tries to impress him by guessing the answers to questions on classical music. Roy's decides that women only like bastards. Jen disagrees, so to settle the argument, Roy puts a fake profile up on an online dating site. Roy and Moss create a horrible online profile, only it works a little too well.

Coming Soon...

Jimmy Carr Hosts the quiz with team captains Sean Lock and Dave Spikey. Guests are Zoe Ball, Scott Capurro, Sally Lindsay and Ben Miller.