Loy Mason, is a hired gun, and somewhat infamous bank robber at least he was. His love interest is Suzy Lamour.  He currently works as hired muscle for Bosch, but he secretly despises him, and is looking for a way to get out from under him and set up a life for him and Suzy.

Loy's personal history not many know and he keeps it close to the chest, all that is known is he is a great shot, and a great bank robber, he has 3 brothers who was all part of the Mason Gang, they all share the wealth of the robberies, but what Loy did with his share no one knows but him. He came to be indebted to and working for Bosch through blackmail, Bosch has his brothers locked up where Loy didn't know but they would all be hung if Loy didn't follow Bosch's every command, true Loy works for him, but he is looking for a way any way to get his brothers out, and himself free with his new love of his life Suzy.

But the reasons behind Loy becoming who he was up to this point and pre bank robberies not too many people know, and Loy only speaks of it to those he truly trusts and there is a reason why he drinks so heavily.