Junior CIA field agent Kelly Kaiser jumps at the chance to lead a risky mission to enter Mexico and gather refugees from under the nose of the notorious drug lord who murdered her fianc�.

When the mission takes a revenge-fuelled twist, Kelly finds herself facing dismissal, but Agnes Pendalon, the CIA's chief 'spook' lady, has other ideas. Kelly must lead a new, top-secret team to hunt down everyone infected by a magical, mysterious rowan tree's supernatural forces, and stop the outbreaks getting out of control. Facing an enemy she cannot see or define, Kelly is pulled into a war between alien forces and humanity, and soon discovers that there is more to her fianc�'s death than meets the eye . . .