What’s Halloween without a serial killer thriller? The “Saw” franchise has held us over for the past decade, but now that it’s dead and buried, Tyler Perry has come to save the day. An adaptation of James Patterson’s bestselling series of crime novels, “Alex Cross” had the potential to surprise everyone, but it’s as flaccid and leaden as its dubstep-heavy trailer.

People have been giving Tyler Perry a lot of flack for attempting a transition into leading-man action roles, but I’m all for it. Martin Lawrence pulled off this kind of balance a decade ago when “Big Momma’s House” and “Bad Boys 2” came out back-to-back, so why not Perry? Replacing Morgan Freeman in the titular role of super-observant detective Alex Cross, Perry is warm and genuine in the scenes with Cross’ family but fails to bring any life to the stale Law and Order grind that takes up most of the runtime.

Let’s talk about Matthew Fox: in his attempt at a career comeback, he plays a serial killer/assassin named “Picasso” who is basically the silliest hipster stereotype I can remember seeing in a Hollywood film. He’s ridiculously skinny, has formal art school training (as evidenced by the disturbing charcoal sketches he leaves at murder scenes), has tattoos so goofy they have to be ironic, and starts wearing a beret around the time he starts personally stalking Cross. With all the weight lost since his role as Jack on “Lost,” his jawline looks more than a little Michael Roth-like, and he manages to keep up an impressive death stare and awkward diction that recall a mid-midterms Adderall overdose. By the climactic chase, he’s clad in skinny jeans and carrying his rocket launcher around in a guitar case. Take a look in the mirror, Wesleyan!

If you were hoping for some good car crashes and explosions, be aware that this movie was made for cheap and director Rob Cohen (“The Fast and the Furious”) has apparently forgotten how to direct action. Some shots in this movie look like they were filmed on a camcorder. The climactic car chase through Detroit is mostly made up of really corny whip-pans, and Perry and Fox’s final brawl is so poorly choreographed it looks improvised.

Aside from its boring incompetence, the biggest problem with “Alex Cross” is its refusal to give in to the genre’s twisted demands. Perry’s brand might have been able to accommodate a more straightforward action movie, but there’s no way he could have convincingly stalked a serial killer without alienating his fanbase. Serial killer hunters are interesting because of how obsessively close they get to their prey, but Perry has to be a paragon of family values even when he’s at the end of his rope. The latent homoeroticism between him and Matthew Fox fizzles; even when he mentions to Fox “the pleasure he’s gonna get when he watches his soul ooze out of his body,” it doesn’t sound creepy and demented enough.

Ultimately, “Alex Cross” doesn’t commit to anything. Mock Matthew Fox if you ever catch it on cable, but don’t waste your money.