The oldest motive in the book. A powerful man. Secret hotel rooms. Late-night phone calls to numbers that don't belong to his wife.

When Callahan pulls the Senator's records, everything seems to fall into place. A wife from a weapons dynasty, humiliated one too many times. A clean crime scene that whispers contract killing. A trail that leads straight back to Amelia Thornton.

But in this case, the obvious answer has a habit of being the wrong one. And the week Grimes spends chasing betrayal in the bedroom may have cost her the real betrayal hiding in plain sight.