In the 19th century, a financially desperate young widow named Rosa Pelham discovers a hidden spring in Berkeley Springs, West Virginia, after her lover falls to his death.

The waters of this spring grant extraordinary longevity. One hundred fifty years later, Rosa and her son, Wyeth, are still alive but deeply burdened by their eternal lives. Their quiet existence is upended when Wyeth's estranged father, Albert, returns with a warning: a major fossil fuel company is drilling nearby, putting their life-sustaining spring at risk of contamination.

The narrative is uniquely watched over and narrated from beyond the grave by the ghost of George Washington, who observes the town's blurring timelines from the local Roman Baths.

The story builds to a midnight climax in the cavernous springs. Rosa, Albert, and Wyeth attempt to protect the source but are followed. When Richie finally locates the spring, he is met by a united front of Wyeth, Pawpaw, and others. A brutal confrontation ensues, leaving Richie gravely injured.

In the aftermath, with secrets exposed and their future hanging in the balance, Rosa and Wyeth are left to finally confront the true emotional and physical cost of their immortal lives.