Woman in Shadow by Carrie Stuart Parks

A woman off the grid.
Darby Graham thinks she’s on a much-needed vacation in remote Idaho to relax. But before she even arrives at the ranch, an earthquake strikes. Then a barn on the edge of town is engulfed in flames and strange problems at the ranch begin to escalate, and Darby finds herself immersed in a chilling mystery.

A town on fire.
More fires erupt around town, and a serial arsonist sends taunting letters to the press after each. As a forensic linguist, this is Darby’s area of expertise . . . but the scars her work has caused her are also the reason she’s trying to escape her life.

A growing darkness.
As the shadows continue moving in, pieces of the town around her come into sharper focus. To make it out alive, Darby must decide if she can trust the one man who sees her clearly.