PRETTY LITTLE LIARS: "A" takes the game up a notch as the PLLs get closer to finding out their identity in an all new episode of ABC Family's hit original series. (Eric McCandless/ABC FAMILY)

The girls of “Pretty Little Liars” (ABC Family at 8 p.m.) are one step closer to finding out the identity of “A” on this week’s episode titled “Bite Your Tongue.” Spencer is onto a new lead from Ali’s diary. Hanna’s love of crime novels leads her back to Ali’s grave, where she finds something shocking with Aria and Emily.

The final five compete in a spring triathlon on the latest “The Biggest Loser” (NBC at 8). The event involves a half-mile swim, a 12-mile bike ride and a three-mile run. Three finalists remain after the weigh-in.

STATE OF THE UNION: Broadcasting across 10 channels and counting, President Obama will address the nation tonight in his fifth “State of the Union” (ABC, C-SPAN, CBS, CNN, Fox, Fox News, Fox Business Network, MSNBC, NBC, PBS at 9). A number of news networks have a few hours dedicated to the expected 90-minute speech with CNN enlisting the help of Wolf Blitzer, Anderson Cooper and Jake Tapper, and Fox News reporting on the event with Bret Baier, anchor of “Special Report.”

RETURNING SHOW: In the second season opener, “Dangerous Grounds” (Travel at 9) opens with Todd facing major danger in Guerrero, Mexico, as he tries to save a deal with a New York City chef by getting his hands on a rumored wine-like coffee.

SERIES PREMIERE: The spirit of the infamous gangster Al Capone still lives on in the form of this drama-filled, lasagna-loving dysfunctional family as they run the family restaurant “Capone’s Restaurant & Pizzeria” on “The Capones” (Reelz at 10). With a notorious family tree and personalities surrounding him, the docu-series’ star, Dom Capone, runs his unkempt crew with an iron fist at the Capone mansion.

Kim introduces a new, quirky wannabe pageant queen to the other girls on “Kim of Queens” (Lifetime at 10) in an effort to motivate them, but the mom has difficulty giving control of her daughter over to Kim.

Actor Eric Stonestreet joins the “Late Show With David Letterman” (CBS at 11:35), with musical guest Bastille.

Comedian Wanda Sykes and actor Thomas Haden Church stop by “The Tonight Show With Jay Leno” (NBC at 11:35), with music from Dwight Yoakam.

Actress Anna Faris is on “Jimmy Kimmel Live” (ABC at 11:35), with a musical performance from Mötley Crüe.

— Rachel Lubitz