Gamma Level: Radioactive

Countdown begins with a suspicious murder in broad daylight, leading Los Angeles Police Department officer Mark Meachum to be recruited to a secret task force of undercover agents from all branches of law enforcement that will investigate the death. But as the truth of a more sinister plot comes into focus, the team must overcome their conflicting personal agendas to unite and save a city of millions.

Seth Meyers, who is Saturday Night Live's longest serving anchor on the show's wildly popular "Weekend Update," takes over as host of NBC's Late Night — home to A-list celebrity guests, memorable comedy and the best in musical talent.

As the Emmy Award-winning head writer for "SNL," Meyers has established a reputation for sharp wit and perfectly timed comedy, and has gained fame for his spot-on jokes and satire. Meyers takes his departure from "SNL" to his new post at "Late Night," as Jimmy Fallon moves to The Tonight Show.

Die Hart follows a fictionalized version of Kevin Hart, who's tired of being the comedic sidekick. He gets his wish when a famous director offers him his dream – to be a leading man action star – but there's a catch: Kevin must first train at the world's greatest action star school, run by a lunatic. Pushed to his limits by this action school coach and a tough-minded rival student, Kevin must survive a series of hilarious, over-the-top action sequences and face his fears if he wants to achieve his dream and land the role of a lifetime.

Who's the toughest in the house? The Ultimate Fighter finds out as mixed martial arts fighters battle it out for a six-figure UFC contract. With two of the top UFC fighters as coaches, contestants will try to kick and punch their way to dominance and to prove who is The Ultimate Fighter.

Tommy Egan cuts all ties and puts New York in his rearview mirror for good when he arrives in Chicago and sets his sights on becoming the biggest drug dealer the Second City has ever seen.