Kill Chain — Meg Gardiner

When a wrecked car belonging to Evan Delaney's father is found at the bottom of a hundred-foot drop, the police suspect suicide, but there's no body. Evan's suspicions of something sinister are confirmed when she receives a call from her father's kidnappers. The ransom isn't money. It's a puzzle -- one that Evan has only seventy-two hours to piece together, as she follows a madman's trail into the very heart of darkness.