The Watchers (The Angelus Trilogy, #1)

Meet Marc Rochat, a man-child who has devoted his life to being the bell ringer at the Gothic Lausanne Cathedral, one of the greatest architectural structures in the world. Eerie things have been going on in and around his church, including tremblings in the underground crypt and a variety of gruesomely murdered bodies showing up in nearby streets. Across the square from the cathedral lives Katherine Taylor, a beautiful young American woman who is making phenomenal money as one of the highest-priced call girls in Switzerland; she's a bit too introspective for her own good and, unfortunately, much too observant of her clients' peccadilloes. Rochat's and Taylor's lives collide with Jay Harper, a British private eye who has been sent to investigate the killings and other strange doings; alas, he has no memory of who hired him or precisely why he was chosen for the job. And now all the clues are pointing skyward, where fallen angels are said to haunt Lausanne.