On an island separated from the mainland by a causeway lives Jaime (Aaron Taylor-Johnson), one of the community's most skilled scavengers. He resides with his wife Isla (Jodie Comer), who is battling a mysterious illness, and their 12-year-old son, Spike (Alfie Williams). As part of the community’s coming-of-age ritual, Jaime takes Spike into the forest to teach him the art of survival and scavenging.
During their trip, they encounter different types of infected, from a fat one to a child. But the most terrifying of them all is an Alpha, a rare variant that is faster, stronger, and smarter than the typical infected. These Alphas are nearly impossible to outrun or outfight, making them a threat to be avoided at all costs.
While staying at an abandoned house, Spike spots a fire in the distance. Jaime mentions that it is probably Ian Kelson (Ralph Fiennes), a former survivor who now lives in isolation. According to locals, Kelson has lost his mind, and most people are afraid of him. However, Spike later discovers that Kelson is actually a doctor. With hope building inside him, he wonders if Kelson might be able to help treat his ailing mother.
Everything changes when Spike witnesses his father having an affair. The betrayal shakes him to the core and becomes the turning point of the story.
Spike decides to break the community’s rules to bring Isla to Kelson, risking everything to save her. With infected still roaming the land and the threat of Alphas making every step more perilous, Spike traverses the dangerous land with courage, love, and a bow in hand.
