Proof that a solid cast can't redeem zero chemistry and terrible writing, "Fam" (9:30 p.m., CBS, TV-PG) debuts.

The new sitcom stars Nina Dobrev as Clem, a perfect wife-to-be with an adoring fiance, Nick (Tone Bell), as well as a troubled past and a dysfunctional family.

Both come to light when her half-sister, Shannon (Odessa Adlon), comes to spend the night, just until her boyfriend can sell enough weed to pay the rent.

Anybody who's ever seen a TV pilot knows the one night will turn into a very long stay and provide the setup for this sitcom.

While we're assured good-girl Clem has a bad-girl past, there is nothing about her that suggests that. There's also little to indicate Nick might be a literature professor, but, hey, this is a sitcom, not Shakespeare.

Shannon is yet another example of why networks should avoid "edgy" characters.

Just last night on ABC's "Schooled," we saw Lainey Lewis (AJ Michalka) go from grunge grrrl to suburban teacher in 10 minutes flat.  On "Fam," Shannon follows a similar trajectory.

It's interesting to note that "Fam" replaces the canceled "Murphy Brown" and borrows story elements from another soon-to-depart CBS comedy, "Happy Together."

Both "Happy" and "Fam" feature a staid couple whose lives are disrupted by a younger, hipper third wheel.

Gary Cole ("Veep") shows up for a few minutes as Clem and Shannon's deadbeat dad, whose abandonment of two girls to a life of drugs and homelessness is played for laughs.

Sheryl Lee Ralph and Brian Stokes Mitchell play Nick's supportive parents. Both are Broadway musical stars, larger-than-life and apt to burst into song.

Rather than enriching "Fam," their presence only adds to the feeling that nothing here quite fits together or makes much sense.

The script includes scenes where buttoned-down types get "stoned" by accident. How trite is the dialogue? When Clem introduces Nick as her fiance, Shannon snarls, "Oh, so you speak French now!"

Help yourself.

- Jettisoned by Fox last spring and quickly revived by NBC, "Brooklyn Nine-Nine" (9 p.m., TV-14) returns for a sixth season.

This frantically silly sitcom is grounded by Andre Braugher's turn as the joyless Capt. Raymond Holt.

He provides the poker-faced gravity that keeps Andy Samberg and the rest of the self-centered, cartoonish cast from flying off into orbit.

Often, not even Braugher is enough. A little "Brooklyn" goes a long way.

- ABC News returns to its greatest hits with "Truth and Lies: Monica" (9 p.m., ABC). Twenty years ago, Barbara Walters earned stellar ratings with a multipart interview with White House intern Monica Lewinsky.

Tonight's other highlights

- Signs of a kidnapping ring on "Gotham" (8 p.m., Fox, TV-14).

- Alara visits her home planet on "The Orville" (9 p.m., Fox, TV-14).

- "Roswell: Mysteries Decoded" (9 p.m., CW, TV-14) returns to well-charted territory.

- Michael makes his case on "The Good Place" (9:30 p.m., NBC, TV-PG).

Series notes

Penny's ex needs a favor on "The Big Bang Theory" (8 p.m., CBS, TV-PG) ... Dwayne Johnson presents "The Titan Games" (8 p.m., NBC, TV-PG) ... Phil sparkles on "Modern Family" (8 p.m., ABC, r, TV-PG) ... Garth to the rescue on "Supernatural" (8 p.m., CW, r, TV-14) ... Sick and tiresome on "Young Sheldon" (8:30 p.m., CBS, TV-PG) ... Stage parents on "The Goldbergs" (8:30 p.m., ABC, r, TV-PG).

Ashtray confidential on "Mom" (9 p.m., CBS, TV-14) ... Undercover in Mexico on "S.W.A.T." (10 p.m., CBS, TV-14) ... A plastic surgeon accused of abuse on "Law & Order: Special Victims Unit" (10 p.m., NBC, TV-14).

Late night

Sen. Kamala Harris (D.-Calif.), Bradley Whitford and Gary Clark Jr. are booked on "The Late Show With Stephen Colbert" (11:35 p.m., CBS) ... Jimmy Fallon welcomes Bryan Cranston, Lana Condor and Love Jones on "The Tonight Show" (11:35 p.m., NBC) ... Claire Foy and Disturbed appear on "Jimmy Kimmel Live" (11:35 p.m., ABC).

John Goodman, Julia Garner, Geoffrey Zakarian and Charlie Hall visit "Late Night With Seth Meyers" (12:35 a.m., NBC) ... Cedric the Entertainer, Ashley Graham and Flatbush Zombies appear on "The Late Late Show With James Corden" (12:35 a.m., CBS).