Mastroianni

But this lonely voyeur with a debilitating neurological disorder — played with haunted energy by star and co-writer Ariella Mastroianni — is a big reason this odd duck of a nerve-jangler compels the way it does.

The movie’s DIY-to-OMG backstory alone is invigorating: A movie-mad New Jersey electrician, director Sloan and his cinephile collaborator Mastroianni crammed in filming on weekends over two years, then shockingly landed “Gazer” in the Directors’ Fortnight at last year’s Cannes Film Festival, an unheard-of triumph for so unpedigreed an entry.

As damaged heroes go, Mastroianni easily keeps our attention and triggers our sympathies for someone who resists the abyss, as near to it as she is.

For one thing, from the tight opening shot on Mastroianni’s eyes, “Gazer” offers that reliable construct of a witnessed crime.

In the role of Guido, Mastroianni is vexed not just by a crisis of creativity but also by the galaxy of women in his life.