Three years after losing her family in a car crash, Grace MacKenna is set to inherit her stepfather's ancestral estate among the mountains of West Virginia. Seeking solace and healing, Grace discovers the ghost of William Kavanaugh, a dashing Civil War captain in Virginia s 17th Infantry, haunts the property. When William charms Grace into investigating the mystery that led to his death a hundred and fifty years ago, she finds herself drawn into a world of chivalry and honor, but also deception with secrets too dark to speak aloud.
Meanwhile, Clay Baxter, home from service in Afghanistan, fights his own demons and ghosts. When Clay senses Grace falling deeper into the realm of the dead, he seeks to pull her back. But is he too late?
Torn between her love for two mysterious young men - one living and one dead - Grace stands in the shadows of the Antietam Battlefield with a choice: one that could leave Grace lost forever, "crossing into the Mystic."