Now this is how you stretch a horror short into a full-length film!

Come Play, writer/director Jacob Chase’s expansion of his 2017 calling card Larry, intelligently upscales its foundation’s technical prowess, slick effects, and command of suspense to the big time in a way that suggest he’s been crafting features for years.

Like any respectable genre peer, its monster — a skeletal entity named Larry — is steeped in social commentary. Activated via a creepy Babadook-like eBook that inexplicably appears on the smart phone of lonely, autistic elementary schooler Oliver (Azhy Robertson, Marriage Story), Larry inspires deep viewer contemplation on humans’ screen addictions and the isolation such activity breeds.

The creature’s layered predatory doings, accompanied by eerie bone-cracking sound effects, makes even more sense in the context of the pending divorce of Oliver’s parents Sarah (Gillian Jacobs) and Marty (John Gallagher Jr., 10 Cloverfield Lane), which makes their already secluded, nonverbal child even more susceptible to Larry’s “charms.”

Though the family’s sightings of Larry via screens — be it at home, especially the neat reveal of his origin story, or during Marty’s graveyard shifts as the attendant of a spookily underused parking lot — are consistently jarring, he’s not the brightest demon. Fairly easy to elude, yet also capable of advanced activity, he’s at best a fledgling menace, still learning his powers, and at worse a victim of inconsistent screenwriting.

Regardless of the explanation, each Larry appearance is a frightful experience and Robertson, Jacobs, and Gallagher Jr. are superb at selling the scares. None of it, however, would work without Chase’s confident vision, which further parlays its thoughtful scares into an effective rallying cry for building lasting friendships and firmly establishes the filmmaker as a talent to watch.

Grade: B. Rated PG-13. Starts Oct. 30 at AMC River Hills 10 and Carolina Cinemark

(Photo: Jasper Savage/Amblin Partners/Focus Features)