Garret Kenning, the Earl of Therneforde, strives daily to conceal the strange secret that had plagued his family for generations. His home, Kenning Old Manor, is dominated by the last remnant of Kenning Castle—the Red Tower. The Tower has the strange capacity to transport people across time, and the constant possibility of peculiar arrivals encroaches on his freedom and his choices. Despite this worry, his life is ordered in comfortable lines with his aunt Lady Margery Kenning as his housekeeper, and his good friend and steward John Debray to support him.

As Therneforde begins to plan his future around marriage to a suitable spinster of his village, the arrival of a traveller from a distant past upsets all his arrangements. He is required, in the following weeks, to reexamine all his beliefs from his opinions of women to his life's most important choices.

Ysmay of Scarsfield's medieval world has changed with a single step. That one stride across the threshold of the Red Tower takes her to a new life, a new family and a new future in a world that is eerily familiar yet distressingly alien. New freedoms beckon, and she is reprieved from a difficult destiny. However, the challenges of adjustment may be too great and her hard-won peace is threatened by a suspicious newcomer to the village.

Reconciling the past and the present and confronting the future present huge obstacles to both Ysmay and Garret. As their world, and the people around them change, they will both require courage and tolerance, and their strength may lie in unity.