When Sergeant Hallie Michaels comes back to South Dakota from Afghanistan on ten days' compassionate leave, her sister Dell's ghost is waiting at the airport to greet her.

The sheriff says that Dell's death was suicide, but Hallie doesn't believe it. Something happened or Dell's ghost wouldn't still be hanging around. Friends and family, mourning Dell's loss, think Hallie's letting her grief interfere with her judgment.

The one person who seems willing to listen is the deputy sheriff, Boyd Davies, who shows up everywhere and helps when he doesn't have to.

As Hallie asks more questions, she attracts new ghosts, women who disappeared without a trace. Soon, someone's trying to beat her up, burn down her father's ranch, and stop her investigation.

Hallie's going to need Boyd, her friends, and all the ghosts she can find to defeat an enemy who has an unimaginable ancient power at his command.