Now entering its fourth season, “Eureka” (8 p.m., Syfy) combines the whimsy of romantic comedy with speculative science. Handsome sheriff Jack Carter (Colin Ferguson) finds himself in a super-secret town filled with the nation’s biggest brains and all of their hairbrained inventions.

Jack is just getting used to the idea that he’s been fired and even applies for a job at Homeland Security, much to the consternation of daughter Zoe (Jordan Hinson), who has settled into the social scene.

To add high-tech insult to bureaucratic injury, Jack finds himself replaced by a robot cop (Ty Olsson, “Men in Trees”), who calls himself Sheriff Andy. Scenes between Jack and his affable cyborg successor offer a humorous contrast between artificial intelligence and human intuition and deductive reasoning — two attributes that are hard to replicate in a software code. Things get particularly hairy when the gravitational forces around Eureka begin to go haywire, but do so in a way that appears to target a particular newcomer.

Much like “Warehouse 13,” its new partner on the SyFy schedule, “Eureka” has a light and breezy feel about it. Scientific breakthroughs, sudden disasters and possible romance appear to lurk behind every corner. As I’ve written before, “Eureka” is the kind of show that networks would have broadcast 15 years ago, a time when series like “Northern Exposure,” “Quantum Leap” and “The X-Files” became cult sensations.

• TCM salutes the films of the late Karl Malden, including “On the Waterfront” (7 p.m.) and “A Streetcar Named Desire” (9 p.m.). Malden, who died last week at the age of 97, turned to television later in his career, most notably in the hit series “The Streets of San Francisco.”

Malden also appeared in a short-lived and little-remembered series, where he played a dedicated steelworker, Pete Skagska, sidelined by a stroke. The show focused on serious topics set against the social backdrop of a tight-knit Serbian-American community that would not be out of place in “The Deer Hunter.” The show put its emphasis on the declining fortunes of blue-collar Americans, a subject that would also be reflected that year in Bruce Springsteen’s album “The River.”

But tough times often prove a boon to TV escapism, not realism. Not even Malden could inspire audiences to watch a story rife with tales of unemployment, impotency and obesity. Or maybe they were just turned off by its title. “Skag” debuted in January 1980 and it was gone after five episodes.

Tonight’s other highlights

• Daniel Radcliffe stars in the 2001 fantasy “Harry Potter and the Sorcerer’s Stone” (6:30 p.m., ABC Family), part of a weekend of Rowling adaptations.

• Breakfast, lunch and disaster on “Chopping Block” (7 p.m., NBC).

• Larry the Cable Guy appears on “Are You Smarter Than a 5th Grader?” (7 p.m., Fox).

• The Dollar General 300 offers NASCAR action (7 p.m., ESPN).

• Artifacts come to life in the 2006 fantasy “Night at the Museum” (7 p.m., FX).

• Eager young protégés hope to crack the Hollywood code in the new sitcom “The Assistants” (7:30 p.m., The N).

• A patient seems dead set on a dangerous procedure on “Mental” (8 p.m., Fox).

• Scheduled on “20/20” (9 p.m., ABC): the rise and decline of General Motors.