The thing about “ticking clock” thrillers, movies with a hard, fast and deadly deadline, is that somebody on board has to be able to tell time. Preferably the director.

That was Job One for James McTeigue (“V for Vendetta,” and nothing remotely as good since) on the set of “Breaking In,” this weekend’s “Woman in peril from home invaders” B-movie. Keep the picture moving, keep the cast on task, amped up and on the edge of panic, maintain that sense of urgency.

Because the guys busting into Gabrielle Union’s dead-dad’s “country house” have only 90s minutes, as they’ve cut the power, before the alarm company calls the cops.

You know the firm. You’ve seen their ads on TV. “Last Alert: You’re already Dead by the Time we Show Up.”

But never mind that. If there’s one thing that Hollywood thrillers and the legions of actors who march through them teach us, it’s that faking shock and breath-gulping panic isn’t easy. And hiding boredom, for some actors, is damned near impossible.

Union, of “Think Like a Man, Too” and “Good Deeds” and “The Birth of a Nation,” is Shaun, a mom who drags her two kids (Ajiona Alexus and Seth Carr) with her to the remote Wisconsin estate that her dad owned. As we’ve seen him run down in the film’s smartly scored, shot and edited opening moments, we know he’s dead. And we know this was no accident, as the “hit and run” didn’t involve any running.

The house is a fortress of stone and brick and bullet proof glass and microchips — quite the security system. But minutes after their arrival, the kids are nabbed by house breakers, and Shaun is forced to master this house, and outfight, outsmart and out trash-talk the gang and its leader, Billy Burke (“Twilight”).

And even though that clock is ticking, even though the power that the bad guys “cut” is somehow on (as is the security system), even AFTER Shaun pulls the circuit breakers and dunks them in a sink, gang boss Eddie (Burke) never breaks a sweat, never for one second lets us think he’s manic, and passing on his hurry to his equally bored team (Mark Furze, Richard Cabral, Levi Meaden).

Burke just mutters “Veerrrrrry impressive” for “a woman alone, trapped by strangers,” and “Moms don’t run, not when their babies are trapped in the nest.” If the man wasn’t bored by “Twilight,” why does he have so much trouble punching the clock here?

And his performance is contagious. Check out the little boy in his most terrified moments. How he doesn’t yawn is a miracle for the ages.

Union, who joins Halle Berry and others who have tackled this “You have no idea what I’m capable of” mom gets down and dirty when her kids are “Taken” genre, gives a little of herself. But she only goes half-Halle in this. The commitment isn’t really there as Shaun half-hearted shouts “I’ll get you out, I love you” to her children.

To her credit, she doesn’t listen when one bad guy, armed with a crowbar, shouts “STOP right there!”

Bad screenwriters (Ryan Engle), do you never learn? NOBODY stops right there.

“Breaking In” far too quickly devolves into unintentional laughs provided by the henchmen, complete with long stretches of near silence, affording the smart alecks in the audience the chance to half-shout, “She’s gonna ELECTROCUTE him,” or “There’s ONE IN THE CHAMBER” and “Shoot SHOOT” at the screen.

The dears. They, at least, have a sense of urgency the folks onscreen forgot. They, at least, can tell time as the minutes tick by in this clock-stopping ticking clock thriller.

MPAA Rating: PG-13 for violence, menace, bloody images, sexual references, and brief strong language

Cast: Gabrielle Union, Billy Burke, Ajiona Alexus, Richard Cabral, Levi Meaden, Christa Miller

Credits:Directed by James McTeigue, script by Ryan Engle. A Universal release.

Running time: 1:28