* Lorna Cartwright: The main character, Dr. Lorna Cartwright, a geneticist who leads a team of researchers sent back in time to study the life of Lady Anne Coventry.
* Dr. James 'Mac' MacKinzie: A member of Lorna Cartwright's team who is also a historian. He serves as the voice of historical accuracy and is constantly reminding Lorna of the importance of not altering the past.
* Lady Anne Coventry: A 17th-century English noblewoman who befriends Lorna Cartwright and becomes the focus of her study.
* Robert Coventry: Lorna's husband, who is also a member of the research team. He is an expert on the history of science.
* The Duke and Duchess of Coventry: Anne Coventry's parents.
* Lord Henry Wilmot: Anne's childhood friend who supports her interest in science.