‘Trap’ Review: Josh Hartnett Plays a Father With a Secret

“Dad, this is the literally the best day of my life,” the teenager Riley (Ariel Donoghue) beams to her doting father, Cooper (Josh Hartnett), in the opening minutes of M. Night Shyamalan’s “Trap.” That feeling won’t last — but for the first half of this mischievous thriller, we’re also having fun.

Riley is ecstatic to have stadium floor seats for her favorite pop icon, Lady Raven (Saleka). The child’s attention is on the stage. Ours is on her father who is having visible difficulty concentrating on the show. He’s clocking the cameras, the exits, the unusual number of cops, the no-nonsense F.B.I. profiler (Hayley Mills) muttering into her walkie-talkie. The police are hunting a serial killer named the Butcher, but all they’ve got to go on is that he’s a middle-aged man in this majority girl crowd. Underneath the thumping bass and the squeals, Shyamalan wordlessly clues us in that the unassuming Cooper is also a slayer desperate to escape.

Instead of telegraphing evil, Hartnett cranks up that gee-willikers likability that once trapped him as one of Hollywood’s factory-stamped generic leading men. At his most devilish, he’s all apple cheeks, grinning so amiably that a merch salesman (Jonathan Langdon) reveals that the Butcher has his own obsessives. When no one’s watching, Cooper’s eyes narrow at whatever is on his mind. Should he pull the fire alarm? Slip through the hydraulic lift in the floor? Can his daughter tell he’s acting weird?

It takes cleverness and control to pull off this unspoken tension. Shyamalan boasts the former and feigns the latter for a while before his hotdogging impulses take over. He’s like a guy who karaokes Hitchcock and then starts ad-libbing his own tune. We’re never onboard with the premise that a 20,000-plus crowd is the perfect place to arrest an unknown man. But we’re willing to play along until it starts to feel like Shyamalan so enjoys being inside Cooper’s head that he doesn’t want to leave. One fairly satisfying ending launches into encore after encore, with Shyamalan holding court past the time the audience is antsy to wrap up.

The plot is at its best when it’s simply a dad, a daughter and the puzzle he must solve to stay in her life. Hartnett and Donoghue have an affectionate, believable chemistry that’s boosted by the young actor’s natural charm — she doesn’t hit a phony note. To root for Riley’s happiness means rooting for Cooper’s, so every so often, particularly after we’ve cheered his latest brazen bit of genius, we’re reminded there’s a victim (Mark Bacolcol) handcuffed in his murder house. Worse, whenever Cooper needs a diversion, he’s willing to send a stranger’s daughter to the E.R.