G is for Gumshoe by Sue Grafton

Good and bad things seem to come in threes for Kinsey Millhone. On her thirty-third birthday she moves back into her renovated apartment, it's really perfect for her, gets hired to find an elderly lady supposedly living in the Mojave Desert by herself, and makes the top of ex-con Tyrone Patty's hit list.

It's this last matter that convinces Kinsey that even she can't handle whoever's been hired to whack her, and she gets herself a bodyguard: Robert Dietz, a Porsche-driving P.I. He takes guarding Kinsey's body very seriously. With Dietz watching her for the merest sign of her usual recklessness, Kinsey plunges into her case. And before it's over, she unearths the gruesome truth about a long-buried betrayal and, in the process, comes face-to-face with her own mortality. . .