Three years after her mother's death, Ruth is finally sorting through her things when she finds a curious relic: a decades-old photograph of her own Norfolk cottage—before she lived there—with a peculiar inscription on the back. Ruth returns to the cot­tage to uncover its meaning as Norfolk's first cases of Covid-19 make headlines, leaving her and Kate to shelter in place there. They struggle to stave off isolation by clapping for frontline workers each evening and befriending a kind neighbor, Zoe, from a distance. Meanwhile, Nelson is investigating a series of deaths of women that may or may not be suicide. When he links a case to an archaeological dis­covery, he breaks curfew to visit Ruth and enlist her help. But the further Nelson investigates the deaths, the closer he gets to Ruth's isolated cot­tage—until Ruth, Zoe, and Kate all go missing, and Nelson is left scrambling to find them before it's too late.