DJ´s Bait in the Box # 73

[This week´s box was sent to me from Tim]

I know that it is horribly unfair to use this brand-new debut for my game, but it happens to be the one I am reading (and some of my readers are the most brilliant detectives) so what you see is what you get:

“Momentarily, my heart palpitates; my hands are clammy with sweat. This must be the nervous thrill that burglars feel. But I won´t steal anything. Emma was the thief, not me. I´ve only ever taken one thing from this house: the back door key. Secretly copied, and then returned to its hook.

I climb quietly up the stairs, avoiding places I know would groan under my weight. Night-lights illuminate the hall, making me blink. Emma´s door is ajar and I can see into the bedroom.”

The Rules:
If you recognize the quotation, or if you think you are able to guess who wrote it, please post a comment. Just leave a hint, do not spoil the fun by giving too much away. The book will be reviewed on Friday or Saturday.