Home Alone meets Mad Max in this atmospheric seasonal chiller, named for Halloween and not a cheery greeting. A disease has wiped out most of humanity, leaving 16-year-old Pumpkin (Milly Shapiro) stranded alone in her rural family home in the middle of nowhere for the best part of four years. This classic American clapboard house has always been the perfect quaint yet unsettling place to celebrate Halloween, and she determines to uphold the family tradition and do just that, sending a radio broadcast to anyone listening to invite them to celebrate spooky season with her. Unfortunately, the message is picked up by some less than wholesome types, led by Thalia (Shannyn Sossamon), thus setting the stage for the proverbial to hit the fan.

It’s the first major screen role for Shapiro since her memorable debut as the little sister in Ari Aster’s Hereditary, and she is in almost every scene here, making for quite the showcase. It’s good casting: Pumpkin is an intriguing presence – at once young and old, presumably because she’s been fending for herself during such a key stage of her development. She’s not had any adult guidance since the age of 12 – arresting her development in some ways, while having to survive, be totally independent and grieve her entire family alone has simultaneously made her unusually tough in others.

This turns out to be invaluable in a horror film; it gives the script plenty of room to have her make naive decisions which are wholly justified, as well as to prove surprisingly resilient in ways that the character’s backstory supports. This gives a plausible, grounded core to the story’s more outlandish trappings, and the splendid production design – ranging from cosy cottagecore Halloween to a timeless Bates motel aesthetic – makes for an appealing storyworld. Hallowarrior is the feature debut of Ben Sottak, an experienced short film-maker, and on this evidence he’s likely to be worth keeping an eye out for.

• Hallowarrior is on Shudder and AMC+ from 16 October.