Jane Crowe, who several years ago accidentally released the plague into the modern world, and her son Alex, with whom her greatest hopes and greatest secret are connected, found shelter in one of the settlements among the survivors of the first wave of the epidemic. But suddenly people start dying from an unknown disease. In search of a remedy for a new scourge, Jane turns to the diary of the medieval doctor Alejandro Sanchez, who survived the invasion of the black plague in Europe in the 14th century.