What We Become (2015) on Netflix

Plot summary

Dino and Pernille live in Sorgenfri with their teenage son Gustav and young daughter Maj. Sonja moves in across the street with her mother Maria, and Gustav takes an interest in her. At a neighborhood picnic, Casper urges Dino to buy a gun for hunting, and Dino refuses. Some picnickers fall ill, throwing up, and elderly Elna arrives saying her husband has died, though his body cannot be found. A virus that turns its hosts hostile spreads through the town. Dino tells the children nothing is wrong. The military seals Sorgenfri, orders everyone to stay inside, wraps the houses in plastic and delivers supplies while the power fails.