While carrying out an autopsy on a body recently brought into a morgue in Santa Fe, county coroner Alexis Cruz makes a surprising discovery. Lodged in the dead man's femur is a musket ball which, carbon dating reveals, was fired some 200 years earlier in the American Civil War. But before she can notify the authorities, Alexis disappears.

The DIA call in Ethan Warner and his partner, Nicola Lopez, to find the missing coroner. But the closer they come to unlocking the terrifying truth, the nearer they unknowingly bring a warped and dangerous individual to achieving a catastrophic goal.