An unknown outbreak suddenly causes people to become violently aggressive, attack others, and spread the condition through bites and exposure to bodily fluids. The crisis spreads rapidly across the city, disrupting electricity, communication, water service, transportation, and emergency response. Mara Reyes and Adrian Villareal meet by chance inside the elevator of the condominium building where they both live. After witnessing the outbreak in the lobby and encountering infected residents on their floor, Mara is forced to take shelter inside Adrian's condominium. Adrian's unusual interest in fermentation and food preservation becomes unexpectedly useful. His pantry contains rice, canned goods, instant food, preserved vegetables, fermented foods, sauces, and other supplies that allow them to remain sheltered for an extended period. They barricade the entrance, store water while it is still available, ration their resources, listen to emergency radio broadcasts, and retrieve supplies from nearby units only when necessary. As the days pass, the condominium becomes their entire world. With danger outside and too much time together inside, the relationship between two strangers slowly changes.