In a world very close to our own, a mother and her young son desperately fend for themselves in the confinement of their one bedroom flat. Five years ago, a toxic microplastics storm killed most of the population. Now Katie must forage and hunt the few surviving animals for meat as she attempts to feed her little boy, to care for him as best she can. At a time when stepping outside could kill you, Harry is kept indoors at all costs, never venturing beyond the entrance to their building, never knowing the truth of how he came to call this place home. Bodies continue to build up around them, inescapable layers of toxic dust hang heavily in the air and Katie is only getting sicker. Then, after years without human contact, Katie and Harry are terrified by the arrival of another survivor and Katie knows she must finally undertake a previously unthinkable journey in search of the man she was supposed to marry.