There were dogs on set and dogs in the script, but Tom Hardy felt like the production of “The Drop” could use one more mutt.

The British actor – known for Bane in “The Dark Knight Rises” and now, he hopes, Bob, the not-so-simple simpleton in the new crime drama penned by “Mystic River” novelist Dennis Lehane – has a hard time saying no to a pooch, or at least something he likes that might make everyone else a little crazy. So when costar Noomi Rapace brought Hardy to an animal shelter near their Brooklyn set to research their roles, the outcome wasn’t in doubt.

“I knew the minute we walked in there, he’d be walking out with a dog,” Rapace said in her trailer on the New York set shortly after the unexpected canine trip.

Hardy did adopt a dog, a pit-bull puppy, and took her to the set. Never mind that the actor was in the U.S. only for a few more weeks. Never mind that he was spending 10 hours each day shooting a movie, then titled “Animal Rescue” before it was changed.

On a chilly April day during the 2013 shoot, Hardy’s new pet was outside the working-class bar where the film is set, jumping, barking and looking a little overwhelmed, or maybe just confused why someone had yet to walk him over to craft services.

“She’s still around, yep. She’s still around,” said Hardy in an interview at the Toronto International Film Festival when asked about the dog. “She has a great home.”

That kind of unexpected behavior characterized Hardy as he made the film, directed by “Bullhead” auteur Michael Roskam and opening Friday after its Toronto premiere last weekend.

Hardy embraced a single-mindedness to play opposite the famously self-critical James Gandolfini (the last movie the late actor shot). Hardy wasn’t bashful in offering suggestions as he watched playback of scenes at the monitors and lobbying Lehane and producers for a more ambiguous ending, which the screenwriter then partly rewrote on set.

He also often indulged in a kind of wild playfulness when Roskam yelled cut, engaging costar Matthias Schoenaerts in what appeared to be a game of unrequited tag and generally getting in touch with his inner child.

“I joke around because if I don’t let it go, it has the counterintuitive effect on the work,” he said in Toronto, puffing on an electronic cigarette.

“Some actors, they can stand still behind a string,” Roskam said. “And with some actors, it’s like they don’t want to over-concentrate and be good when you’re not shooting, and then you say action and they lose it. Tom is one of those actors.”

“The Drop” is a mood piece of double-crosses and beaten-down humans, of dog rescues that are metaphors for lost innocence. Lehane makes his feature-screenwriting debut with the film, adapting the script from his short story. Shot by Nicolas Karakatsanis in the brackish palettes and confined spaces of working-class Brooklyn, “The Drop” has the kind of muted tone and slow-burn pacing one doesn’t see much of in American thrillers these days.

“What I was trying to do was go back into a very authentic era of film noir,” Roskam said. “The average person thinks of noir, and they think of shadows on the ceiling and a femme fatale and a guy with a smoke. For me, it’s a social comment, a voice for the voiceless. I wanted to direct this film as if Frank Capra would have done ‘Taxi Driver.'”

That’s in part why the film was shot entirely on location in and around the neighborhood of Marine Park, a working-class enclave that’s just a few miles from hipster Brooklyn but a time zone away in sensibility. There is a blue-collar bar, named for Bob’s cousin Marv (Gandolfini), who is sort of like Tony Soprano but without the success. Once its owner, Marv has lost the bar to a group of Chechen mobsters who use it as a “drop” point for money laundering.

At the start of the film, a robbery has the mobsters putting the screws to Marv and bartender Bob. Meanwhile, Hardy’s character, a low-key and possibly slow-witted man, has rescued a pit bull pup.

While he and damaged new friend Nadia (Rapace) bond over the dog, a creepy neighborhood man (Schoenaerts) claims the dog is his. The mobster and canine plot lines soon entwine – especially as the dog takes on a role that may be a MacGuffin but certainly serves a character purpose.

Lehane said he created the animal-themed short story as a new spin on his traditional crime tales and found himself able to revise it significantly because the source material didn’t offer many elaborations.

“I couldn’t do this with ‘Mystic River,’ because I’d keep thinking, ‘I worked so hard to get to Page 301, so how can I change what’s on Page 299?'” he said. “But a short story is different.”

What he built is a story that has a surprising poignancy amid the machinations and violence. There’s a kind of heartbreak beneath many of the proceedings, shady as they are.

“We’re all desperate, and we all want something, but there’s a tenderness here too,” Schoenaerts said.

The movie also offers the chance for viewers to see two actors of considerable talent share the screen in a posthumous bonus of sorts.

As he sat next to Michael Gandolfini – Hardy had allowed the late actor’s teenage son to shadow him over the course of several interviews – he described Gandolfini using one of his go-to run-on phrases and extended metaphors (“The melody and music and tonalities is what we were trying, and we were looking for a space to harmonize”) and noted Gandolfini’s perfectionism.

“He didn’t like to get things wrong. If things weren’t going the way he wanted it to, he made very specific demands to accomplish his level of expectations. He would get mad at himself. It was, ‘I’m going to get this right.’ He would police himself.”

That allowed the pair, Hardy said, to build a rapport necessary for the film.

“It really is an odd couple story,” he said, “in a strange way a ‘Mice and Men’ story.”