A ridiculous movie, even for M. Night Shyamalan

One thing I’ll say about “Trap” — it’s got a spot-on title.

After the theater lights go down, director M. Night Shyamalan’s latest spitball is an awfully long sit, even if at one hour and 45 minutes it’s not really that long a movie. 

The reason “Trap” feels so endless is because Sir Twist-A-Lot drops his biggest bombshell right at the start (not to mention in the movie trailer).

Main man Cooper (Josh Hartnett), a sweet dad who’s taking his daughter Riley (Ariel Donoghue) to the concert of a Taylor Swift-ish pop star called Lady Raven, is also secretly a prolific serial killer known as “The Butcher.” 

Believing the anonymous criminal will be at the oddly-timed afternoon show, the FBI uses the opportunity to finally apprehend him after seven years and 12 brutal slayings. 

The plan was concocted when the police discovered a torn concert ticket receipt in one of the Butcher’s abandoned lairs. 

That nearly all tickets are purchased online today is one of many beyond-lazy details that make this entire story impossible to buy into. Next to “Trap,” “The Village” is practically a documentary.

In any case, the feds flood the venue to track down a man who fits the murderer’s description: 30-something and white with a tiny rabbit tattoo on his wrist.

By the time Cooper discovers the ruse, he’s already inside with Riley, and the place is locked down.

That, in and of itself, is not an un-fun premise. But the next hour or so drags as the pathological pop frantically contemplates methods of escape while his teen daughter shrieks at her favorite songstress (Shyamalan’s daughter Saleka Shyamalan).

Being that “Trap” takes place in a run-of-the-mill arena, the means to an exit are, well, doors. Hard to fashion much of a thriller out of a series of metal doors.

Not to be deterred, Shyamalan tries to make Cooper skulking around and stealing staff keycards more interesting than it is by introducing a supposedly brilliant British serial killer profiler named Dr. Grant. 

Played by Hayley Mills, the doc uses her decades of expertise to deduce that the criminal will possibly pull the fire alarm to create a distraction or attempt to sneak backstage.

Um, I majored in theater at a state school and I could’ve told them that.

And the security shouldn’t need to be informed of anything. Cooper’s total lack of discretion — breaking into rooms and causing a ruckus in full view of carefully monitored video feeds — would, you’d think, be a giant red flag for the hundreds of officers swarming the premises. 

So would Hartnett’s erratic, laughing-gas performance — a turn that’s less adrenaline-fueled than coked-up. The actor is much too cuckoo for the viewer to consider his character a dangerous and credible threat.

But I got the impression Shyamalan desperately wants us to. 

The writer-director’s problem there is that psychoanalyzing serial killers has been a cottage industry in Hollywood for decades. And Cooper is no Hannibal Lecter or Dexter.

When Shyamalan wades into more cerebral territory — there’s talk of a “monster” inside of Cooper’s head, for instance, and he has visions of older women taunting him — the film turns even more preposterous than it already was. 

Of course, with the “Sixth Sense” director, the question on everybody’s lips is “What about twists?”

There aren’t really game-changing shocks here so much as detours. Shyamalan takes what your non-serial-killer father might call the scenic route.

The destination? Meh.