“WILL & GRACE” (9:30 p.m., NBC, TV-14) returns from hiatus and quickly picks up its well-worn formula. Jack bursts in just as Will wraps up a session with some of the law students he’s been mentoring. He deludes himself into thinking he’s the “cool” faculty member they’d rather hang out with, but they rush out to a late-night gathering with people their own age.

Employing a plot device even older than Will, or for that matter, “Will & Grace,” a show that debuted in 1998, the kids leave a jar of chocolate milk in Will’s fridge. Will and Jack chug from the glass bottle, enthralled by a taste from their youth. Karen arrives to glance over some of Will’s notes on her divorce papers and joins them in a swig. All three soon discover that the juvenile beverage was merely a delivery system for a hallucinogenic party drug, sending all three into raptures of trippy beauty and poignant emotional truths.

Meanwhile, Grace has some realizations of her own while simultaneously contending with her slacker sister, Janet (Mary McCormack, “The Kids are Alright”), and a demanding client (guest star Chelsea Handler) with designs on Janet.

As it always has, “Will & Grace” continually dances between naughty and nice, casual hedonism and blatant sentimentality, caustic wisecracks and episodes that end with lessons and hugs.

For those keeping score, this marks a new timeslot for the show, putting it up against the comedy “Fam” on CBS, a series that tries to be as “edgy” as “Will & Grace” but fails spectacularly. It’s also the timeslot that “Murphy Brown” held, another reboot like “Will & Grace.” But one that showed its age almost immediately.

The critical failures of those rival series don’t make “Will & Grace” seem any fresher, but they do demonstrate just how difficult it can be to consistently pull off that show’s form of comedy. It’s all about cast and chemistry.

Other highlights

• It’s never too early to get in the holiday spirit! Bill Murray and Andie MacDowell star in the 1993 comedy “Groundhog Day” (6:45 p.m., IFC).

• Military reinforcements arrive on “Gotham” (8 p.m., Fox, TV-14).

• Meredith comforts her ailing father on “Grey’s Anatomy” (8 p.m., ABC, TV-14).

• New mermaid arrivals are hard to hide on “Siren” (8 p.m., Freeform, TV-14).

• A robot created in the form of a young boy (Haley Joel Osment) tries to discover his place in the universe in the 2001 science-fiction thriller “A.I.: Artificial Intelligence” (8 p.m., TMC), a project begun by director Stanley Kubrick and completed by Steven Spielberg.

• Gordon offers Bortus grooming tips on “The Orville” (9 p.m., Fox, TV-14).

• Details emerge concerning Jon’s death on “A Million Little Things” (9 p.m., ABC, TV-14).

• Nate has an agenda on “How to Get Away With Murder” (10 p.m., ABC, TV-14).

Cult choice

Janet Gaynor and Fredric March star in the original 1937 incarnation of “A Star Is Born” (9:45 p.m., TCM), a melodrama about a boozy idol eclipsed by his up-and-coming wife, a film rebooted in 1954, 1976 and 2018. The most recent “Star” has been nominated for eight Academy Awards.

Series notes

Sheldon’s dilemma on “The Big Bang Theory” (8 p.m., CBS, TV-PG) ... Dwayne Johnson presents “The Titan Games” (8 p.m., NBC, TV-PG) ... Nick confronts his past on “Supernatural” (8 p.m., CW, TV-14) ... Placating a bully on “Young Sheldon” (8:30 p.m., CBS, TV-PG).

Christy’s sponsor proves hard to manipulate on “Mom” (9 p.m., CBS, TV-14) ... Pawns and kings on “Brooklyn Nine-Nine” (9 p.m., NBC, TV-14) ... A monster feeds upon fear on “Legacies” (9 p.m., CW, TV-14) ... Shannon’s mother sends mixed messages on “Fam” (9:30 p.m., CBS, TV-14).

Terrorists demand a ransom on “S.W.A.T.” (10 p.m., CBS, TV-14) ... A teen’s story doesn’t add up on “Law & Order: Special Victims Unit” (10 p.m., NBC, TV-14).

Late night

Matt LeBlanc and Gary Gulman appear on “Conan” (11 p.m., TBS) ... Jimmy Fallon welcomes Seth Meyers, Danai Gurira and Dan White on “The Tonight Show” (11:35 p.m., NBC) ... Viggo Mortensen, Rita Moreno and Summer Walker appear on “Jimmy Kimmel Live” (11:35 p.m., ABC).

Busy Phillips, Conan Gray and Brendan Buckley visit “Late Night With Seth Meyers” (12:35 a.m., NBC) ... Justin Hartley, Dominic West, Elle King and Migos are scheduled to appear on “The Late Late Show With James Corden” (12:35 a.m., CBS, r).