In 2024, the world faces the dire consequences of a mutated virus known as COVID-23, plunging societies into their fourth year of quarantine. In the United States, the government has transformed into a fascist police state, compelling citizens to take temperature checks via their cell phones. Those infected are forcibly taken from their homes and placed in quarantine camps—dubbed "Q-Zones"—where survival becomes a brutal struggle. In these camps, the infected are often left to either die or recover under harsh conditions.
Among the chaos, Nico Price, portrayed by K.J. Apa, stands out as a motorbike courier with immunity due to his past infection. He shares a virtual relationship with Sara Garcia, played by Sofia Carson, who lives with her grandmother, Lita—an elderly woman currently in lockdown, preventing any physical contact between the two. Nico works under Lester, played by Craig Robinson, a proprietor of a package delivery service catering to the affluent. One of their prominent clients is the Griffin family, consisting of Piper and William, whose daughter Emma, portrayed by Lia McHugh, struggles with an auto-immune disorder. William, a former record executive, is romantically involved with May, a singer thriving online by selling her renditions of classic songs. Interestingly, May forms a connection with Michael Dozer, a disabled war veteran and drone operator working with Lester to monitor their couriers.
The tension escalates one night when Lita begins exhibiting symptoms, coinciding with the efforts of the "sanitation" department, led by Emmett Harland, to remove a neighbor named Alice who is also infected. Harland's ruthless measures include a shocking murder of an infected individual trying to escape a Q-zone. In distress, Sara reaches out to Nico about Lita's worsening condition. Nico pledges to protect Sara amidst her growing fears. After a failed temperature check for Lita, Nico's determination to shield Sara from being taken intensifies.
In a harrowing twist, Nico discovers that Lester is implicated in transporting illegal immunity wristbands, with the Griffins at the helm of the operation. Upon infiltrating their home under the guise of business, he receives a contact number for their alleged supplier but soon realizes he has fallen into a trap laid by Harland. Narrowly escaping, the urgency amplifies when tragedy strikes—Lita passes away, and with Harland's department closing in on Sara, she dons a hazmat suit and escapes, though capture is imminent.
Tension mounts with William's desperate attempts to rendezvous with May, who is reluctant due to past threats. The friction escalates to violence as William attempts to eliminate May. However, Dozer, showcasing his skills, employs a weaponized drone to intervene and save May—the dynamics between these characters growing ever more complex.
Nico's return to confront Piper sheds light on the illegal dealings, and when fueled by the passion to save Sara, Piper reluctantly provides Nico with an immunity wristband. A final showdown ensues as Nico confronts Harland, leading to a deadly altercation. In a race against time, Nico succeeds in slipping the immunity bracelet onto Sara, ensuring her safety just as the authorities move in.
As they finally embrace, Sara reveals her true immunity to Nico, and the plot reaches a fulfilling climax. In a twist of justice, Piper and May orchestrate a plan to implicate William and Harland for their illegal activities. Meanwhile, May and Dozer spark a budding romance, while Nico expresses his gratitude to Lester by sending his own immunity bracelet back. The film concludes with an inspiring scene as Nico and Sara journey along the beautiful Pacific Coast Highway, embracing their newfound love and freedom.
