It begins with sentiment, introducing a character worthy of our sympathy, if not our pity.

There’s an emotional tug to the scenes in which the guy with the genetic malady connects with that cute co-worker who seems to “get” him.

Sure, “the old ultra-violence” is coming, over-the-top and played for laughs. But there’s something to be said for having the grace to humanize your characters before you cartoonize them.

“Novocaine” is a gonzo action farce about an ordinary loner, an office drone born with an inability to feel pain. When first tested, he’s anything but brave. But take away a person who means something to him, and he gets there. A quick learner, we see him doing the calculus involved with confronting murderous goons.

How much damage would I do myself if I clock this guy with a searing-hot frying pan that will cook my hand? Can I kill this other guy with the tip of the crossbow bolt sticking out of my leg? How much pain can a tattoo artist tolerate from the tool of his trade?

Co-directed by the “Villains” and “Significant Other” team of Dan Berk and Robert Olson and scripted by Lars Jacobson, “Novocaine” tests the viewer’s tolerance for pain in an action comedy that mimics “Kick-Ass.” But confined to events of a single, frantic day, the filmmakers would have been better served checking out the manic mayhem of “Crank.”

“Novocaine” is a classic 88 minute film wrapped in a 110 minute package. Once the action kicks in with a bank robbery, it just lurches to a halt in between the half a dozen set-piece fights they cook up for our misfit millennial.

Nate, an assistant manager at a credit union, rises to the occasion. Jack Quaid, as that guy nicknamed Novocaine by the jerks in his middle school, likewise delivers the goods.

But the movie never gets up to speed, never manages much more than a stagger when it should pass by at a “don’t-overthink-this” sprint.

Nate, a gawky video gamer so conditioned to avoid injury that he won’t eat solid food — “I might bite my tongue off” and not feel it — is transformed into “a superhero” in the presence of Sherry, played by Amber Midthunder of “Prey.” She’s new to the San Diego credit union where they work.

Sure, he’s assistant manager and thus her boss and should, by rights and policy, steer clear. But she’s curious to the point of “interested.” When he’s with her, he’ll even try solid food –cherry pie, of course.

But that’s the day before three armed Santas barge into the bank, shooting and torturing and murdering the manager, clobbering Nate and taking Sherry hostage.

When he wakes up and realizes they’ve outgunned the first cops on the scene, good guy Nate gives first aid to a downed officer, steals his cruiser and sidearm, and sets out to save the first woman who’s ever paid the least bit of attention to him.

Three robbers? That’s three fights in his future, to say nothing of the hulking tattoo artist (Garth Collins) who might help him find his way to the “gang” that emptied the vault he was so reluctant to open for them.

Giving our hero a sad, underexplained past and lonely present pays off.

“When you don’t have anybody to care about, it’s harder to get hurt,” is the message here.

But the filmmakers did more research on Nate’s real-world condition — CIPA, Congenital Insensitivity to Pain — than most anything else in the “real” world of the movie.

Employee protocols during a bank robbery to no-dating-your-underlings edicts to police procedure — Betty Gabriel and Matt Walsh play the detectives who wryly sleepwalk through this “ticking clock” scenario — to the way the justice system really works are bent to suit the lazy contrivances of the screenwriter of “Day of the Dead: Bloodline.”

Jacob Batalon, Spider-Man’s latest sidekick, is introduced as a gamer/”friend” who helps the hero, and the movie’s shortcomings are underlined in this character and this performance. He’s been funnier in literally every other action comedy/comic book film he’s been in.

Midthunder struggles with the script’s efforts to complicate her character. Ray Nicholson, as the leader of the robber gang, is over the top in the most conventional ways.

Quaid, the son Dennis Quaid and Meg Ryan, is at his best in the scenes that humanize Nate — a compassionate loan officer who cuts a customer some slack, a first aid addict who cares for others before he gets around to the self-surgery he needs to complete to keep from bleeding out between the brawls he almost always loses right up to the moment he doesn’t.

But the movie around him shuffles and lurches along, a narrative that unfolds in fits and starts. Thrillers live on tension and rising suspense. This one discards suspense too early. And action comedies are, by design, fast and furious. This one, while serving up some serioulsy gory action and splatter film laughs, can’t get out of its own way.

Rating: R for strong bloody violence, grisly images, and profanity. Lots of profanity.

Cast: Jack Quaid, Amber Midthunder, Ray Nicholson, Betty Gabriel, Matt Walsh and Jacob Batalon

Credits: Directed by Dan Berk and Robert Olsen, scripted by Lars Jacobson. A Paramount release.

Running time: 1:50