Take one part “Hannah Montana” and add one of the oldest sitcom gimmicks in the books and chase with an aging (or is that ageless?) TV star in search of a second, third or 15th comeback and you’ve got “Ruby & the Rockits” (7:30 p.m., ABC Family).

David Cassidy stars as David Gallagher, half of a brother act of New Wave rockers called The Rockits, who were hot for a minute or two in the late 1980s. His estranged brother, Patrick (Patrick Cassidy), now leads the sedate life with a wife (Katie Amanda Keane), an SUV dealership and two precocious teenage boys.

David continues to perform, coasting on the fumes of his former fame and playing at ever-smaller venues. His delusions end when he discovers that he has a teenage daughter, Ruby (Alexa Vega).

At first, David tries to shirk instant fatherhood by fobbing Ruby off on his brother. But gosh darn it, things happen. Do you think the appearance of this chipper and talented chanteuse will stir domestic feelings in one brother and sprinkle showbiz stardust in the eyes of another? Gee, I dunno.

For those over 9, “Rockits” is best appreciated as an example of how performers try to alter the expiration dates on the milk cartons of their careers. Cassidy, a popular, charming and handsome TV star from the early 1970s, tries to pass himself off here as someone 20 years younger. By the late 1980s, the real Cassidy was already well into the “where-are-they-now” phase. In 1991, he appeared in the odd cult comedy “Spirit of ’76,” a spoof on 1970s nostalgia. It wasn’t exactly a hit, but it’s 100 times more original and interesting than “Ruby.”

• Take “Survivor” and add a dash of “Mad Max” and you have “The Colony” (9 p.m., Discovery). This social experiment/reality series takes 10 volunteers from various walks of life who pretend that they’ve survived an earth-shattering cataclysm. They hole up in an abandoned warehouse in a rough end of Los Angeles and try to survive and plan for a future world.

Every so often, the producers send in “marauders” to challenge their domain by rattling the fences and doors and riding by on loud motorcycles and shaking their fists. They look like extras from a Dee Snider video. Experts also chime in, offering their take on the participants, telling us that they’ve internalized their situation and that they actually believe that they’ve survived the end of the world. I’m glad someone does.

Tonight’s other highlights

• Two helpings of “America’s Got Talent” (7 p.m. and 8 p.m., NBC).

• I would watch “Hell’s Kitchen” (7 p.m., Fox) only to see Gordon Ramsay beaten senseless with a spatula.

• “Nova ScienceNow” (8 p.m., PBS, check local listings) explores taste and smell, carbon capture and intelligent walruses and sea lions.

• “California in Crisis” (8 p.m., CNBC) looks at that state’s not-so-golden finances.

• Dolly Parton visits the expansive brood on “18 Kids and Counting” (8 p.m., TLC).

• “Medium” (9 p.m., CBS) moves to its new network.

• Tommy’s temper earns him a grim assignment on “Rescue Me” (9 p.m., FX).

• “The Betrayal” on “P.O.V.” (9 p.m., PBS, check local listings) follows refugees from Laos to New York over several decades.

• “Real Sports with Bryant Gumbel” (9 p.m., HBO) recalls a Super Bowl no-show.