Tonight, the CW launches “Beauty and the Beast” (8 p.m.), a less-than-enchanting adaptation that fits well within the network’s schedule of dark, violent fantasies.

The action begins with mystery and bloodshed. Working her way through law school as a bartender, the beautiful and petite Catherine “Cat” Chandler (Kristin Kreuk, “Smallville”) is set upon by machine gun-wielding bad guys who slaughter her mother before her eyes. And ours. Cat looks like a goner as well until she is saved by an otherworldly creature that quickly disappears.

The show fast-forwards to the present day, where Cat is now working as a sassy New York police detective teamed with the no-nonsense Tess Vargas (Nina Lisandrello, “Nurse Jackie”). While investigating the death of a model in a posh hotel, they come upon a strange anomaly. Fingerprints on the victim belong to Vincent Keller (Jay Ryan, “Terra Nova”), a doctor-turned-soldier reported dead in Afghanistan a decade earlier.

Cat’s sleuthing leads her to Vincent, who is holed up in an abandoned factory and protected by his nerdy best friend, mad scientist J.T. Forbes (Austin Basis, “Life Unexpected”). Cat discovers that Vincent was part of a military experiment gone awry and that he remains the loose end of a conspiracy that nefarious government types want to terminate.

Vincent isn’t the first real or fictional character to have gone off to war or another adventure only to return with the fear that he left his humanity behind. He’s got good company on the CW. Characters on “Nikita,” ”Arrow” and “The Vampire Diaries” have all been transformed into something monstrous. And the guys on “Supernatural” spend half their time traveling to and from hell. There sure are a lot of pretty things on the CW. Pretty disturbing things.

• Vice President Joe Biden and his challenger, Rep. Paul Ryan, meet in the Vice Presidential Debate (8 p.m., ABC, CBS, NBC, Fox, CNN, Fox News, C-SPAN, CNBC, MSNBC).

Tonight’s season premieres

• Elena adjusts to her new nonlifestyle on “The Vampire Diaries” (7 p.m., CW).

• Dennis and Dee face a life or death choice on “It’s Always Sunny in Philadelphia” (9 p.m., FX).

• The gang anticipates a new NFL draft and a new baby, in that order, on “The League” (9:30 p.m., FX).