A funny thing happens on the season finale of “House” (7 p.m., Fox): An episode of “ER” breaks out. The kind where a hospital procedural becomes a combat zone. A high-cost production that screams “Sweeps,” where something really BIG just has to happen.

The absence of such stunts is one of the reasons why many viewers have gravitated to “House” from “ER,” but I guess they just couldn’t help themselves.

This “House” departs from the series norms to take House and Cuddy to the scene of a horrific urban construction accident. Just before departing for the gruesome site, House learns that Cuddy has become engaged. Just how much her new status affects the dyspeptic doctor’s psyche is something Cuddy, House and the audience will have to figure out.

Once among first responders, House returns to normal, barking out diagnoses and making triage assessments with his usual bemused detachment. Surrounded by death and chaos, he gossips on the phone and vandalizes a soot-covered vending ma-chine to steal a soda.

Then he begins to act strangely. Hearing a noise in the rubble, House crawls into a tight crevice to find a young woman pinned beneath the building. And as hard as he might try not to, he seems to bond with her pain and predicament. Some fans of the series may feel a tad uncomfortable seeing a patient get to House. And the rest of us have to figure out whether this change in attitude marks a dramatic breakthrough or a major setback.

• “Animal Planet Investigates” (9 p.m., Animal Planet) follows the Humane Society during an investigation of the chain store Petland, suspected of dealing in dogs raised in puppy mills where dogs are bred in squalid conditions.

• Young people search for their dream job and their first job on “Hired” (5:30 p.m., MTV), a new documentary series following job seekers in various fields, from shoe design to event planning.

Tonight’s season finales

• The gang heads for Utah on “One Tree Hill” (7 p.m., CW).

• Blair mulls an affair to remember on “Gossip Girl” (8 p.m., CW).

• The investigation of an agent’s murder brings Beckett and Castle closer together on “Castle” (9 p.m., ABC).

Tonight’s other highlights

• Chuck keeps his job secret from his father (Scott Bakula) on “Chuck” (7 p.m., NBC).

• The Yankees host the Red Sox (7 p.m., ESPN).

• A stabbing victim’s double life emerges after death on a two-hour episode of “Law & Order” (8 p.m., NBC).

• Jack’s hunt for the truth complicates Taylor’s efforts on “24” (8 p.m., Fox).

• A bomb kills Horatio’s ex on “CSI: Miami” (9 p.m., CBS).