As she crosses the Atlantic, powerful magics are being worked by Lady Sarah Roxbury. Lying on her deathbed, Roxbury casts a spell that will summon her counterpart from the universe-next-door... Sarah.

Waking, Sarah finds herself in a world not her own, a world where the Stuart kings still rule England, where Baltimore and the original thirteen United States are still British colonies, where Napoleon runs rampant on the European continent, a world where she is the Lady Roxbury. Under the influence of a steady supply of drugs and insidious manipulation, Sarah comes to believe that she is Roxbury, and soon finds herself embroiled deep in the machinations of court intrigue and scandal. She also comes to despise her intended, the Duke of Wessex.

As the threat of a French invasion grows, the only hope for England is a peace treaty with Denmark. But when the Princess of Denmark goes missing and France's agent, the Marquis de Sade, is found in council with Denmark's king, it is up to Sarah and Wessex to put aside their differences.