A Perfect Lie by SM Thomas

Abigail Berry is in her forties, married, and has spent the last two decades making herself forgettable. Laundry, dinner, small talk with neighbours - a life built, deliberately, to look like nothing. Then a stranger arrives at her door and says a name she hasn't heard in twenty years. Before the conversation is over, he's dead on her kitchen floor, and her husband Owen is standing in the doorway asking what she's done. What he doesn't know yet is that she's done this before - professionally, for people who don't forgive debts and don't forget faces. Now Abigail has a body to hide, a past that isn't finished with her, and a husband who has to decide how well he really wants to know his wife. And if Owen decides enough is enough, then Abigail always knows where she can bury a body.