Spotted: lonely boy. And he’s a long, long way from the Upper East Side.

Far from the cardigans, text messages and damsels in distress that helped make him famous on television’s “Gossip Girl,” Penn Badgley strips down to a more emotional level as he takes on a new level of drama on the silver screen in his first starring role in “The Stepfather.”

In this remake of the 1987 movie of the same name, Badgley plays Michael Harding, a troubled teen who returns from military school to find his mother, Susan (Sela Ward, “The Guardian”), cozied up with new “Daddy” David Harris (Dylan Walsh, TV’s “Nip/Tuck”), a man whose obsessive desire to craft the perfect home life easily alienates Michael from the rest of the family.

As if his somber persona on “Gossip Girl” wasn’t contemplative enough, Badgley takes Michael to the edge of brooding and beyond as he attempts to expose his new stepfather’s dastardly — and deadly — ways.

“He’s borderline petulant. I really didn’t want to make him petulant, but he’s sort of pissed off coming back from military reform school,” Badgley said in a recent conference call. “He’s partially reformed, but he’s definitely bitter a little bit from the whole experience and not sure how to approach his family. So, he’s quiet and he’s almost insolent.”

But this film wasn’t just another practice in Dan Humphrey wit and one-liners. Chasing Serena Van der Woodsen through the streets of Manhattan offers its health benefits, but Badgley said “The Stepfather” gave the actors their fair share of exercise.

“I had to do stuff that I never had [to do] in a role, which was really fun,” Badgley said. “I really loved embracing the physicality of it. Before all these scenes where you’re having to run around a house being chased by a murderer, to make that real, you kind of have to exhaust yourself. At least what I was doing was doing pushups, pull-ups, screaming and letting the blood rush to my head, and drooling a little bit even. I mean, I probably looked like an idiot in between takes, but I was just trying to exhaust myself to make those moments real.”

The film itself also takes a different avenue than the norm, deviating from the standard Hollywood slasher films and gross-out gore. A seemingly more Hitchcockian exploration of suspense than the disembowelment horror blockbusters like those of the “Saw” lineage or Rob Zombie flicks, Badgley said “The Stepfather” takes a harder look at the psychological factors behind trust, betrayal and, consequently, fear.

“It’s a simpler, story-driven thriller. It isn’t full of twists and turns,” Badgley said. “You know who the killer is from the first frame of the movie. It’s explained in the beginning. So rather than it being the age-old game of Clue where you’re wondering who it is, it’s really a different kind of thrill. It’s really like a really tense dread, where you’re waiting for the other shoe to drop and wondering how it’s going to happen.”

He may be battling a murderer, but Badgley asserts this film, and especially this role, is more palatable even than the character he portrays on the small screen. Exploring the issues associated with the sanctity of family relates very much to a modern audience, especially given the high rates of separation and divorce now.

“It’s really going to resonate with a lot of kids, and a lot of adults, too,” said Badgley, whose parents have been separated for a number of years. “If there’s anything that anybody can relate to, it’s any issues that you can relate back to family.”