Life isn't easy for six-year-old Rebecca. With her parents at each other's throats, a big sister with her own worries, and an uncle who makes her take her medicine, it's hard for Rebecca to keep smiling. Especially since she's fallen sick, and her parents want to keep her inside all the time. But Rebecca has a solution to her problems: her microbe friend Ernest. He'll try to reconcile her parents while fighting off a new virus named Sam, who threatens to make Rebecca's health take a turn for the worse!