As paranoid thrillers go, “Sightless” isn’t half bad before it — pardon me — loses its way. And even after that, it manages a moment or two even as it frustrates you with its many blown possibilities.

The story of a concert violinist blinded in a seemingly random attack ,who starts to wonder if it was random at all during a strange “arranged” convalescence, the debut feature of writer-director Cooper Karl gets all wrapped up in its implied conspiracy, in “the mystery.”

And then, in resolving that mystery, it goes completely off the rails. I mean, we can’t expect “Wait Until Dark” or “In Darkness” every time out. But come on.

Madelaine Petsch of TV’s “Riverdale” stars as Ellen, battered and sprayed in the face in an attack that leaves her blind. She can’t get a hint of “Who DID this to me?” from the cop (Jarrod Crawford) on her case, or anybody else.

But her brother overseas arranges for a caregiver and a new apartment “downtown” (Seattle). And this new guy, Clayton (Alexander Koch of “Black Bear”) is all empathy and expertise when it comes to dealing with how to condition someone for a new life without sight — giving her that first cane, instructing her on text-to-voice/voice-to-text emailing, etc.

But lost in her head, Ellen ponders who might have a grudge against her, or her ex-husband. She wonders why she can’t reach her best friend, Sasha. Brother Easton is still in Japan and hasn’t come home to help.

“I can’t get ahold of…ANYone!”

And with her new heightened focus on sound, Ellen wonders about the background noises she hears and the creepy stuff going on next door. Lana (December Ensminger) and Russo (Lee Jones) are having…problems. Is Clayton her savior, she wonders? Or she should trust him at all?

Clever touches include the way Ellen imagines this or that person as she speaks to them and visualizes the new world surrounding her. Might a violinist have more acute hearing?

Clayton’s suggestion that her world’s images can be “whatever you want” now seems neither helpful nor on the up and up.

Koch gives us a hint of mystery if not menace as the caregiver, and Petsch plays petulant diva well enough.

But writer-director Karl doesn’t make the imagined threats palpable and the peril logical in the least. News flash, shouting “I can hear you BREATHING” is not going to save you from an intruder when you’re a petite fiddle player.

And that finale… Somebody’s been watching Christopher Nolan pictures and not taking away the right lessons in plot twist tricks from them.

MPA Rating: TV-14, violence

Cast: Madelaine Petsch, Alexander Koch, December Ensminger and Lee Jones.

Credits: Scripted and directed by Cooper Karl. A MarVista film on Netflix

Running time: 1:29