Proof that the worst sitcoms can be based on true life tales, “Accidentally On Purpose” (7:30 p.m., CBS) adapts the memoirs of writer Mary F. Pols, who found herself “accidentally” pregnant after a fling with a much younger man.

Jenna Elfman of “Dharma & Greg” fame stars as Billie, an effervescent but unattached newspaper movie critic on the shady side of 35 who has recently concluded a three-year relationship with her rich but shallow boss, James (Grant Show).

As soon as you can say “rebound,” she has a torrid affair with a much younger Zack (Jon Foster), a guy who sleeps on an unmade mattress on the floor. Give “Accidentally” some credit for avoiding the consequence-free sexual snark of shows like “Two and a Half Men.” Consequences arrive within weeks, and to her surprise, her “boy toy” steps up to the plate in ways that her yuppie boss never would.

This may be Pols’ story, but it’s Elfman’s show. And she protects her turf like an enraged polar bear. Stars of successful shows share the spotlight with a strong supporting cast. “I Love Lucy,” “Seinfeld” and “Will & Grace” were about so much more than the names in the title. In contrast, Elfman has surrounded herself with ciphers and barely functioning cliché stereotypes of the office cad, the office gossip, the overbearing sister and a brash young guy and his posse of witless and stoned slackers. The working title of this failed sitcom should be “Dharma Gets Knocked Up by the Dell Dude.” But that would be funny, and this show is not.

• After a season of delusion and deception, “House” (7 p.m., Fox) returns to harsh realities. House finds himself in a psychiatric facility, a chance to come to grips with problems that transcend his pain-killer addiction and get to the heart of his misery and misanthropy.

In lesser hands, this could be sappy, but “House” presents a strong and assured movie-length detour from the series’ main narrative and a chance for star Hugh Laurie to interact with a strong ensemble cast of guest stars, most notably Andre Braugher as the clinic director. Lin-Manuel Miranda is also strong as House’s motor-mouthed roommate, and Franka Potente as a hospital visitor who helps the cranky MD live in the moment.

For “House” buffs, this is unmissable. Some may chafe at the episode’s brief descent into sentiment, but others may recognize that that’s just what the doctor ordered.

• Produced by Forest Whitaker, the five-part series “Brick City” (9 p.m., Sundance, airing every night this week), focuses on the challenges facing the beleaguered city of Newark, N.J., and its young mayor, Cory Booker.

Tonight’s season premieres

• Barney and Robin become a public item on “How I Met Your Mother” (7 p.m., CBS).

• Claire adjusts to college on “Heroes” (7 p.m., NBC).

• “Dancing with the Stars” (7 p.m., ABC) begins its ninth season.

• Two is a crowd on “Two and a Half Men” (8 p.m., CBS).

• Sheldon leaves for Texas in a huff on “The Big Bang Theory” (8:30 p.m., CBS).

• As Delco struggles to survive, Horatio enters deep flashback mode on “CSI: Miami” (9 p.m., CBS).

• Castle toils on his new novel and frets about Beckett on “Castle” (9 p.m., ABC).

Tonight’s other highlights

• Two backpackers take off for some seriously unbeaten paths on the new series “Madventures” (Travel), exploring Brazil (9 p.m.) and Southeast Asia (9:30 p.m.). Originally a TV hit in Finland.

• President Barack Obama is scheduled on “Late Show with David Letterman” (10:35 p.m., CBS).