Namesake by Sue MacLeod
Two Jane Greys. One secret.
It started with a history project. Mr. Gregor assigned a research paper on a figure from the Tudor era, and of course Jane Grey had to pick her namesake - Lady Jane Grey, the fifteen-year-old girl whose parents schemed to place her on the throne of England, then abandoned her to face the executioner. The project is engrossing from the start, but when Jane opens a mysterious prayer book and finds herself in the Tower of London in 1553, she finds herself literally drawn into her namesake's story.
Soon, Jane is slipping into the past whenever the present becomes too unbearable, avoiding her mother's demands, her best friend's fickleness, her crush's indifference. In the Tower she plays chess with the imprisoned Lady Jane, awed by her new friend's strength and courage. And it is in the Tower, keeping vigil as the day of the execution draws near, that Jane learns that she, too, must have the courage to fight for her own happiness.
Suspenseful, emotional and powerful.-Kirkus Reviews