GLEE: Elliott (played by guest star Adam Lambert), Kurt and Dani (guest star Demi Lovato) perform in an episode entitled “Trio.” (Adam Rose/FOX)

“American Idol” alums Adam Lambert and Demi Lovato join “Glee” (Fox at 8 p.m.) this week to sing with Kurt, and Elliott (played by Lambert) finds himself enmeshed in Rachel and Santana’s fight.

Emily confronts Ezra and Mona in her quest for answers on “Pretty Little Liars” (ABC Family at 8), while Hanna goes on to track a new lead in Alison’s case after she speaks to the police.

The first few minutes of “NCIS” (CBS at 8) are intense when DiNozzo (Michael Weatherly) confronts a man impersonating a Navy officer and, once guns are drawn, the perpetrator is killed, with the only witness being DiNozzo’s father.

Blind auditions continue on “The Voice” (NBC at 8) with Blake Shelton, Shakira and Usher on the judging panel.

Jess moves into Nick’s bedroom, but that causes major personal-space issues on “New Girl” (Fox at 9), while Coach also wants more space from Cece once he thinks that she’s treating him like one of her girlfriends.

Sam and Dean investigate the death of a young girl on “Supernatural” (CW at 9), and things seem routine until they realize a link in the case to a ghostly presence.

It’s Tactical Village Day on “Brooklyn Nine-Nine” (Fox at 9:30), a day of training courses and competition for regional precincts, during which Amy runs into an ex-boyfriend.

RETURNING SHOW: “The Little Couple” (TLC at 10) returns for its sixth season, and on the opener the couple travels to India to adopt their new daughter, Zoey, but while abroad, Jen falls ill and receives a troubling diagnosis.

In a “Chopped” (Food at 10) episode entitled “Grandma v. Grandma,” four grandmothers go head-to-head in a challenge that involves bacon grease, meatloaf mix and oatmeal.

SERIES PREMIERE: Craftsmen Ray Villafane, Andy Bergholtz and their team carve masterpieces from a variety of mediums on “Carvers” (Syfy at 10), including pumpkins, ice, wood, chocolate, sand and even meat.

Comedian Chelsea Handler and actress Lea Michele are on “The Tonight Show Starring Jimmy Fallon” (NBC at 11:35).

Actor Michael Keaton stops by the “Late Show With David Letterman” (CBS at 11:35), with musical guest Phantogram.

Actors Jane Lynch and Omar Epps come to “Jimmy Kimmel Live” (ABC at 11:35), with music from Amos Lee.

— Rachel Lubitz