In All in a Garden Green, thirteen-year-old Erica Pickins walks through a door of the old manor house, Hengrave Hall, on a family visit to England and finds herself mistaken for the elder daughter of the house, Margaret, in the year 1578. Queen Elizabeth herself is about to arrive on a royal visit, and, because of her musical talent, Erica becomes the most important part of the desperate attempts by the Catholic family to entertain the Protestant Queen.
Erica chooses to play along and pretend that she is Margaret. With a little help from her brainy friend Pedro, and after making a few whopping social blunders in welcoming the Queen of England, Erica manages to pull off her final performance—but not before the real Margaret reappears at exactly the wrong moment.