Velocity

Like many Koontz books, this one had a great hook that gave a lot of promises, most - but not all - fulfilled. Bartender Billy finds himself trapped as a madman begins leaving him notes, suggesting that Billy is in control of choosing to take action and cause a grisly death, or side with inaction and still be responsible for something an equally horrific death. I don't think Koontz quite delivered on that promise, but he made a good run at it.