Having always preferred the company of microbes, British scientist Kesta Shelley has spent her life peering through a microscope rather than cultivating personal relationships. That changed when Kesta met Tim—her cheerleader, her best friend, her absolute everything. So when he was one of the last people in London to be infected with a perplexing virus that left the city ravaged, Kesta went into triage mode. Although the government rounded up and disposed of all the infected, Kesta is able to keep her husband (un)alive—and hidden—with resources from the hospital where she works. She spends her days reviewing biopsy slides and her evenings caring for him, but he’s clearly declining. The sedatives aren’t working like they used to, and his violent outbursts are becoming more frequent. As Kesta races against the clock, her colleagues start noticing changes in her behavior and appearance. Her care for Tim has spiraled into absolute obsession. Whispers circulate that a top-secret lab is working on a cure, and Kesta clings to the possibility of being recruited, but can she save her husband before he is discovered?