Park Chen has spent most of his life as a killer-a deadly, deep cover operative known as the Bone Collector. Now, he's been benched. Reassigned as an instructor at Project Watchtower, he's tasked with training a school of psychopathic assassins while trying to keep a promise to his friends. Gift Ayutthaya isn't treated like a gift at all. If anything, his parents treat him as a burden, though a spoiled one...