That’s one cool dog saving lives (and the heroine) in ‘Megan Leavey’

Not the dog!

As a general rule, movie audiences tend to care more about dogs than humans.

Think about it. In many a movie, we barely shrug when extraneous supporting characters (or a bunch of unseen extras) are eliminated — but if the lovable family dog hears something in the deep night, goes out to investigate, and is found dead on the porch in the morning, the entire audience groans and gasps.

In the sometimes overly sentimental but inspirational and moving “Megan Leavey,” the title character AND her beloved dog Rex risk their lives multiple times and perhaps even sustain harm (see the movie please), and it’s tribute to the quality of the script and to Kate Mara’s outstanding work that we care at least as much about the human as the canine.

That’s no flippant remark, no backhanded compliment of Mara’s performance. Because the dog we’re talking about here is one of the coolest, most heroic and ultimately most lovable canines in movie history.

Based on a true story, “Megan Leavey” follows the classic blueprints of both the buddy movie and the redemption story. That one of the “buddies” is a German shepherd with a surly disposition and a bone-cracking bite doesn’t make the story any less formulaic — or any less involving.

When we meet Mara’s Megan, she’s listless, directionless, unable to hold down a job and on the verge of getting tossed out of the house by her nagging mother (Edie Falco), who cheated on her father (Bradley Whitford) and is now living with Dad’s hard-drinking, unemployed former best friend (Will Patton).

Out of boredom and desperation more than anything else, Megan signs up with the Marines — but she’s on the verge of screwing that up as well when she finally makes a connection and finds a purpose.

That purpose is named Rex. He’s a fierce and noble but temperamental K-9 Marine dog with the same problem as Megan; neither one of them is particularly good at bonding with human beings.

Actor-composer-singer-artist Common plays the obligatory tough-but-compassionate Gunnery sergeant (of course he’s known as “Gunny”) in charge of the K-9 unit. Common pretty much channels Louis Gossett Jr.’s character in “An Officer and a Gentleman,” and that’s not a bad launching point for creating a character.

Rex snarls and growls and bites. Megan refuses to give up on Rex. They become inseparable, and the connection only grows stronger when they’re shipped off to Iraq.

By this time, we’ve met some likable supporting characters, including Ramon Rodriguez as a fellow dog handler who falls hard for Megan, and Tom Felton (Draco Malfoy in the “Harry Potter” movies) showing some nice range and proving he can play a genuine good guy — a dog handler who has been through several tours of duty and is something of a legend in the Corps.

Director Gabriela Cowperthwaite (making her feature film debut on the heels of the great documentary “Blackfish”) does a fine job with the combat sequences. We hold our breath as Megan and Rex search apartment complexes and roam the harsh desert in search of IED’s. We’re almost certain a bomb is going to go off at one point — but when it does, it’s still a stunning and potentially heartbreaking moment.

“Megan Leavey” is even more effective in the final act, as Megan struggles with PTSD and falls back into a pattern of self-pity and distancing herself from human contact. She becomes consumed, to the point of obsession, with reconnecting with Rex and adopting him, even though Gunny tells her it’s not a good idea, because Rex is a soldier, not a pet, and there’s a strong chance he’ll have a very hard time assimilating to civilian life. (Which of course is exactly what is happening with Megan.)

Kate Mara delivers one of the best performances of her career in the title role. Megan can be a self-centered brat, and it’s not always easy to like her — but thanks to Rex, she does learn what it means to love something as much or more as one loves oneself. Corny and clichéd, to be sure — but I dare you to resist Megan and Rex, especially in the last five minutes (and the closing credits) of this movie.

★★★1⁄2

Bleecker Street presents a film directed by Gabriela Cowperthwaite and written by Pamela Gray, Annie Mumolo and Tim Lovestedt. Rated PG-13 (for war violence, language, suggestive material, and thematic elements). Running time: 116 minutes. Opens Friday at local theaters.