X by Sue Grafton
A glamorous redhead wants to locate the son she put up for adoption thirty-two years ago – an easy two hundred bucks for P.I. Kinsey Millhone. But when Kinsey finds she was paid with marked bills, and her client is nowhere to be found, it becomes clear the mystery woman has something to hide.
Meanwhile, in helping the widow of an old friend – the recently murdered PI Pete Wolinsky – with some paperwork, Kinsey uncovers a link between the late investigator and an unhinged man with a history of ruining lives. As Kinsey investigates this sociopath further, she soon becomes his next target. Now Kinsey must prove her case against him, before she becomes his next victim.