The new governess, Miss Jean Muir, has arrived at Coventry House to begin the task of teaching 16-year-old Bella music, French, and drawing. Mrs. Coventry, Bella's mother, has agreed to allow Miss Muir thirty days to see if she is able to accept the educational schedule for which she is hired. After Miss Muir demonstrates her skills to the satisfaction of Mrs. Coventry, brothers Edward and Gerald, and cousin Lucia, she is shown to her living quarters. When she is alone and the curtains are drawn, she pours herself an ardent cordial from a flask she pulls out of her luggage and thinks about her plans for the next day. She has told the mother that she is nineteen years old, but when she removes her makeup and braids she is suddenly 30 and falls asleep quickly and deeply. A complicated scheme of romance and rebellion, cunning and courtesy, stagecraft and assistance is slowly untangled as she uses her accomplishments and sympathies to work her way to the very heart of the Coventry family, Sir John. Her sights are set on his kindliness and generosity to make her socially accepted. Ned and Gerald, all the servants, and even Ned's wildish horse fall in love with her. She warns them ..".beware of me in time, for against my will I may do you harm." The final days are fast-paced and precisely measured out to create a consummation of the intended event, much like the grand performance results from several careful rehearsals.