When Hiro travels three years into the past, he has a second chance to save Charlie from the hands of Sylar. However, Samuel's presence serves to complicate Hiro's mission even further. Elsewhere, H.R.G.'s past with his Primatech partner is revealed.

Even though they do their best in order to be the perfect couple, Barney's attitude of know-it-all lands him in trouble with Robin and they are forced to seek Marshall and Lily for advice.

Quinn comes to Clay's rescue as he reels from a tragedy while Dan and Rachel's history comes back to bite them.

While Jenn awaits her test results, Cassie is invited to New York City for her birthday and Lizzie takes a dramatic turn.

Concerned about the impact of over-fishing, host Alton Brown explores tasty and extremely sustainable farm-raised trout.

In the seventh week of the competition the couples first have to dance an unlearned dance from week 1 to 6 and then they will either dance the Paso Doble or the Tango in teams.

Yasir is determined to win the bid to renovate the church even if it results in bankrupting him in the process.

Zack's plan to surprise Billie with a newly-installed low flow toilet leads to an unpleasant outcome as he and Billie get into their first major squabble.

Alan's advice to Chelsea that she get breast-reduction surgery is not met with enthusiasm by Charlie.

Will Cappie's and Casey finally get back together? And if so, what does this mean for Cappie and Evan's friendship. Will Ashley be supportive? As one of the biggest blue ribbon competitions Songfest is approaching, the ZBZs are determined to win it all.

Olivia says something she regrets during her appearance on Jimmy Fallon's talkshow and tries to keep Dan from finding out. With election day around the corner, Nate suspects his grandfather will stop at nothing to get Trip elected to congress. In the midst of another feud with Serena, Blair befriends a new "it" girl and takes her to an election night party at Chuck's hotel, hoping to make Serena jealous.

The tables are turned as Nancy and Glenn find themselves on opposing sides of a trauma. Elsewhere, the on-scene priorities of Boone are questioned, and Rabbit has a surprising reaction while treating a patient.

Sheldon becomes Leonard's teacher in order to understand football, while an incident with flying a kite threatens Howard and Raj's friendship.

Horatio and the team investigate a groom's disappearance when two groomsmen wake up without any memory of the insane bachelor party not long before.

Rita and Patty get into a fight after an audition goes sour. Meanwhile Hallie goes to a college party without Rita's permission after being told by Patty's son to pursue higher education, which leads Rita and Patty to reconcile in order to find her.

An up-and-coming rock star's body is found in a scene that appears staged from her recent music video.

The Jay Leno Show welcomes comedians Hamish and Andy, singer Mariah Carey and a performance by Cirque du Soleil.

Coming Soon...

Hallie and Kip try to reconcile their friendship although they are no longer a couple. Meanwhile, Rita and Jay become friends with the parents of Shannon's classmate Brianna, but they are caught in an awkward situation when Shannon decides to end her friendship with her.

Sen. Bob Menendez

Nicholas Thompson

Julia Louis-Dreyfus, Guy Fieri, Carrie Underwood

The Tonight Show with Conan O'Brien welcomes guests actor Ewan McGregor, snowboarder Shaun White, and a musical performance by Tegan and Sara.

Isane and Iba come face to face with Ashisogi Jizou, Tobiume and Haineko. It is then up to Hinamori and Matsumoto to help them out. Soi Fon continues her fight against Gonryoumaru and Tengen but things quickly become more complicated when Suzumebachi joins the fray. Ayasegawa is also having a hard time in his fight against Ruri'iro Kujaku. Meanwhile, Ichigo and Senbonzakura are both going all out to end their own fight.

Elliot finds it hard to run the ward without Connie. Penny discovers that he is suffering with angina. Vanessa appoints a new locum registrar. Joseph, Faye and Faye's mother attend Archie's funeral. Judith is given bad news about her divorce settlement. Maria returns to work.

Black holes are one of the most destructive forces in the universe, capable of tearing a planet apart and swallowing an entire star. Yet scientists now believe they could hold the key to answering the ultimate question - what was there before the Big Bang? The trouble is that researching them is next to impossible. Black holes are by definition invisible and there's no scientific theory able to explain them. Despite these obvious obstacles, Horizon meets the astronomers attempting to image a black hole for the very first time and the theoretical physicists getting ever closer to unlocking their mysteries. It's a story that takes us into the heart of a black hole and to the very edge of what we think we know about the universe.