Sometimes, they lose you in the finale. They over-explain their “motiveless murder” thriller, and the explanations don’t add up to anything other than “pitiless psychopath” or the filmmakers do something else to show they don’t know when to call it a day.

“Stalker” is a half-decent iteration of the popular “identify theft” thriller, starting with “pranks” and transitioning to house breaking, thefts, and utter identity destruction, all of it with a side order of murderous stalker.

It flirts with “stylish,” and is just paranoid enough — if a little slow — as we watch our new-to-California teacher/tutor (Vincent Van Horn) meet somebody nice in a bar (Christine Ko), take a rideshare back to her place, and see his life steadily unravel as the Ryde dude (Michael Lee Joplin) befriends him, clings to him and then turns on him.

Director and co-writer Tyler Savage samples all manner of ID theft horrors and pitches his movie somewhere in the “Cape Fear” to “Cable Guy” as B-movie range, switching points of view from hapless Andy (Van Horn) to predatory Roger (Joplin) as he does.

Van Horn’s Andy experiences the downward spiral of a life he’s lost control of, a wrong he cannot rectify. The performance captures a little sense of the despair (crawling into a bottle), a hint of the rage. Portraying a teacher, it’s a toned-down turn that feels something like a cheat.

The inevitable “I didn’t mean to trigger you” and Why are you doing this?” get our victim nowhere. The cops seem amused at the destructive “pranks” the apparent master criminal is able to pull on Andy. And cell phone expert gives him the “see this all the time” shrug.

“You got sim-swapped.”

All of which is set up in a workaday Los Angeles firmly rooted in reality. How would you “punish” a freelance tutor? Send him to bogus “appointments” (a drug dealer’s house) for starters.

But the “reality” and the suspense and the narrowly-defined “entertainment value” dissipates in an ending that talks its way out of any sense the story might have made and any sense of satisfaction the viewer might have hoped for.

MPA Rating: unrated, bloody violence, sexual situations, profanity, alcohol abuse

Cast: Vincent Van Horn, Christine Ko, Michael Lee Joplin

Credits: Directed by Tyler Savage, script by Dash Hawkins, Tyler Savage. A Vertical release.

Running time: 1:26