In early 2000s West Tisbury, five-year-old Sam Permar began making films. He would spend hours drawing animations frame by frame until he could bind them together flipbook-style. He would then premier his creations for his sister, Tessa Permar, complete with promotional posters and MPAA ratings.

“Sammy came out of the womb making movies,” Ms. Permar said.

Twenty years and six semesters of film school later, Mr. Permar has returned to his filmmaking roots on the Vineyard, this time with a professional camera and a cast and crew of 14.

On Wednesday, he wrapped filming on his original short film, Tick, a dark satire of the Island’s tick-borne illness epidemic. The film serves as Mr. Permar’s master’s thesis, and was shot entirely on Menemsha Beach and at his mother and sister’s house in West Tisbury.

The story involves two entitled vacationers, Rebecca and Jonathan, whose Vineyard getaway is disrupted by rashes and an onslaught of other physical and mental symptoms. Between medical misinformation and their own denial, they cannot escape a fate that evokes the writhing body horror of Ari Aster’s Hereditary.

Tessa and Sam Permar. — Ray Ewing

The couple’s illness consumes them whole, denaturing and disfiguring their bodies until they transform into ticks themselves.

“It combines horror with absurd comedy. That’s my goal,” Mr. Permar said.

His film aims to underscore the failure of the healthcare system to diagnose his characters’ tick-borne illnesses, but also their own negligence. Needing to strike this balance posed a challenge: How could he create decadent and irresponsible characters without sacrificing their likability? He found his answer deep in the annals of reality television.

“During winter break, I binge-watched like 10 seasons of Vanderpump Rules, and the scripts just poured out,” he said.

Though Ms. Permar started out as her brother’s biggest fan, Tick turned her into his collaborator. In addition to serving as producer, she choreographed every scene and helped out with administrative gaps, including heading up craft services.

A typical day on set for Tessa might have started with leading actors through the undulations that convey human-to-tick metamorphosis and ended with preparing three different flavors of quiche.

Her brother’s project is also a personal one for the family. Like many Islanders, the siblings contracted Lyme as children. A doctor spotted Mr. Permar’s bullseye-shaped rash from across a beach and urged his parents to put him on an antibiotic. Meanwhile, Ms. Permar’s Lyme went undetected and she now copes with chronic Lyme.

Ms. Permar says she is now a “Lyme disease advocate.” When neighbors or friends notice a rash and feel fluish, she is one of their first calls. She feels her brother’s film isn’t just art, it’s a conduit for crucial public knowledge. The film’s exaggerated horror represents a very real danger.

“I just feel really seen, even though it’s not about me at all,” she said.

Mr. Permar said that the 18-minute film’s eventual release will represent about two years of work, from writing the script and generating funding to post-production work. The end of filming means it is time for editing and scoring the movie.

For Mr. Permar, the magic of Tick reaches beyond its spooky sardonicism and the rush of realizing a dream. He loved working with his crew, including his sister and several of his classmates at Emerson Unviversity Film School. He will, in turn, help his classmates with their master’s theses.

“Most of us have worked together a lot, so we have that experience of working through problems in the moment,” Mr. Permar said. “We have that history.”

On Monday, when the sun began to set over Menemsha Beach, the cast and crew rushed to the shoreline for a group photo. Everyone proudly wore their custom Tick Crew T-shirts.

Mr. Permar never stopped grinning.

“It’s the funnest,” he said.