Jamie Aldrich is ready to begin the next chapter of her life. After dealing with a series of discomfiting events that began with the loss of her husband two years ago, she's taking a well-earned vacation with her fiancé, Sam Mazie, in Oklahoma's Osage Hills State Park. But her newfound serenity is disrupted when she and Sam hear a scream and find the body of an elderly woman on a hiking trail. Park ranger Doug Moyer calls it an accident, the result of a falling tree branch. Jamie isn't so sure.
Soon after, while exploring the park, Sam and Jamie discover a surprising inscription on a crumbling wall: "Patrick Gallagher loves Mary Jamison, 1954." Mary is Jamie's mother, but Jamie has never heard of Patrick. Her mother refuses to explain, as usual. When Sam disappears after smoke fills their cabin, it is clear that something strange and sinister is afoot in the park. To save her fiancé -- and herself -- Jamie will have to unravel the ties between the mysterious death of the recluse and her mother's first love, and also determine what truth lies behind tall tales of gangsters' loot, ghosts, and secret affairs.