Seventeen years after the disappearance and murder of Lily Morgan, her brother Det. Luke Morgan receives a letter from the killer who calls himself The Professor. The killer claims "23 pretty little girls harvested dead" - and he's not done.
It's the clue Luke has been hoping for all these years, but can he really trust a serial killer at his word? When the killer strikes a little too close to home, Luke is hot on his trail - the killer taunting him at every turn. Meanwhile Luke's investigative team - private investigators Riley Sullivan and Cooper Deagnan - work to unravel long-forgotten cold cases across states and uncover decades old witnesses who still have stories to tell.
The cat and mouse game has only just begun. Luke, Riley and Cooper must stop a diabolical serial killer before he goes underground until the next harvest.
Just how far will Luke go to bring his sister's killer to justice?