After nearly three decades of isolation on Lindisfarne Island, Jamie (Aaron Taylor‑Johnson), his wife Isla (Jodie Comer), and their 12‑year‑old son Spike (Alfie Williams) venture to the mainland seeking medical help for Isla’s unexplained terminal illness. They discover that the Rage Virus has evolved into terrifying new strains—“Slow Lows” and deadly “Alphas,” including one named Samson .

During their journey, Dr. Ian Kelson (Ralph Fiennes) reveals Isla’s prognosis is incurable, leading her to undertake an emotional assisted suicide that brings closure and dignity . Spike escapes with a baby girl born infection‑free from an Alpha mother, underscoring a fragile hope . In the film’s tense finale, Spike is rescued by an older, charismatic cult‑leader Jimmy (Jack O’Connell)—formerly infected—hinting at a dark new world and setting up the next chapter, The Bone Temple.