Trying to find some normalcy during the Covid-19 pandemic, Brian Murphy and his family are on a summer excursion in Cape Cod when his wife, Emma, comes down with concerning flu-like symptoms. But their leisurely return home to New York City quickly becomes a race to the local hospital as she suddenly begins seizing in the car. At the ICU, she is diagnosed with eastern equine encephalitis, a rare and highly lethal mosquito-borne viral disease seemingly caught during one of their evening cookouts. Complicating the situation further, Brian and Emma’s young daughter then begins to exhibit alarming physical and behavioral symptoms, too.