Watchers and Whispers are two of Dean Koontz's best. Shattered isn't quite as good, but it's still a good read that will only take you a day or two to finish.
First of all, Watchers is a MUST read. I was skeptical that it could be *THAT* good, but it was. It's brilliant, unforgettable, and at times, a tear jerker. It's about a lonely, depressed man named Travis and a lonely, "homely" sheltered creepmouse of woman, Nora who are brought together by a super-intelligent golden retriever who's escaped from a government lab. Meanwhile, a vicious failed experiment of a creature has also escaped, intent on killing the dog, whom the couple adopt and name Einstein. It's when we learn WHY the creature wants to kill Einstein, when we learn MORE about this terrifying creature that makes our hearts break and the tears flow. Watchers features a truly sympathetic bad guy, and the character's development and progress (espescially Nora's) throughout the story are amazing to watch. There's also a sub-plot in the first half of the story with a psychotic cable guy stalking Nora. Wonderful book, rivaled only by the excellent Intensity as Koontz's best.
Whispers is also a fantastic book. An aquintance sneaks into a semi-famous screenwriter's house and tries to kill and violate her. She kills him, and one day he shows up at her house again, apparently having risen from the grave. Unfortunately, everyone, save for one police officer, thinks she's either mistaken, nuts, or lieing for attention. Eventually we learn that the villian is actually convinced that the female protagonist is his mother risen from the dead, in another body. Why does does he despise his mother so much? What are the nightmares about "whispers" that he has every night about? How could Bruno still be around when he's been killed? There is, of course, a budding romance between the officer and the female protagonist, and there's also a very *detailed* sex scene. One scene where the villian rapes and murders a young woman is very disturbing and somewhat graphic.
Shattered is the lesser of the three, but it's still a good book, and a nice, quick, simple read just like The Face Of Fear is. It's about a guy and his eleven year old brother who are driving across the country to meet his fiance Courtney. Unfortunately, Courtney's jealous ex just so happens to be trailing them, along for the ride, and determined to kill him. He tries to break into their hotel room one night and even wields an ax in one scene.
Overall, this is a great place to start when it comes to Dean Koontz. I'm currently reading my 16th Koontz book, and I highly recommend:
The Door To December
The Bad Place