Merry Primrose Ramsey lives in England with her parents and her imaginary friend, Molly. At the outbreak of World War II, she is sent to live with her relatives in America, in a small town called Rose Valley. On the way over she meets a real best friend named Molly, who eventually moves to Rose Valey, too. Merry and her American cousin Jerry take to each other immediately and find all kinds of adventures, including rescuing a carrier pigeon and going fishing alone.
Merry's new life is not without trials. She misses her parents. She gets teased at school for the way she talks. Her puppy unravels the scarf she has spent weeks knitting for her daddy far away in England. But Merry's birthday more than makes up for it. Her aunt finds primroses for her to pick and make into primrose chains as she had always done in England on her birthday. And best of all, her new school friends give her a wonderful surprise birthday party.