'GRIMM': Adalind and her baby are threatened by Prince Viktor and a new powerful enemy. (Scott Green/NBC)

Brian Williams hosts “108 Hours: Inside the Hunt for the Boston Marathon Bombers” (NBC at 8 p.m.), a breakdown of the time that elapsed between the bombing and capture of the second suspect.

RETURNING SHOW: On the Season 6 opener of “Kitchen Nightmares” (Fox at 8), chef Gordon Ramsay pays a visit to the defiant owners of Amy’s Baking Co. and the owner of a Denver pizzeria.

FINALE WATCH: “The Neighbors” (ABC at 8:30) Season 2 wraps up with Larry struggling to figure out where he can live after he finds out he’s pregnant.

The documentary “Mad Dog: Inside the Secret World of Moammar Gaddafi” (Showtime at 9) takes viewers into the Libyan despot’s world, as told by those who knew him and worked for him.

Viktor enlists the help of a dangerous ally to hunt down Adalind and her baby on “Grimm” (NBC at 9) while Nick and his mother tirelessly work to stop him.

“Live From Lincoln Center” (WETA at 9:30 and MPT at 10:30) brings us a performance from Jason Isbell, formerly of the Drive-By Truckers, who plays hits from his 2013 “Southeastern” album.

Jack’s star pupil (played by guest star Anna Chlumsky) is found alive, which means the team could be one step closer to finding out the Chesapeake Ripper’s identity on “Hannibal” (NBC at 10).

Danny and Baez investigate the murder of an affluent professor who happened to be involved with a shady scholarship program on “Blue Bloods” (CBS at 10).

SERIES PREMIERE: “Boss Hog” (Discovery at 10) follows Brian “Pigman” Quaca and his crew as they take on Texas’s wild hog program.

“Real Time With Bill Maher” (HBO at 10) hosts a roundtable with actor Rob Lowe, Rep. Duncan D. Hunter (R-Calif.), journalists Ana Marie Cox and Matt Taibbi, Pussy Riot members Masha Alekhina and Nadya Tolokonnikova, and Tolokonnikova’s husband, Petya Verzilov.

Actors Nicolas Cage and Emily VanCamp are on “The Tonight Show Starring Jimmy Fallon” (NBC at 11:35), and rock band Kiss performs.

Former president Bill Clinton stops by “Jimmy Kimmel Live” (ABC at 11:35), along with professional boxer Manny Pacquiao.

Following a 2014 Masters Tournament highlights special, actors Tom Selleck and Carrie Brownstein come to “Late Show With David Letterman” (CBS at 11:50), with music from country artist David Nail.

Rachel Lubitz