Koko is the first book in Peter Straub's "Blue Rose" trilogy, but it stands alone quite well.
Dr. Michael Poole and three of his friends--all former members of his unit in Vietnam--travel to Washington D.C. for the opening of the Vietnam War Memorial. While there, they discuss a spree of grisly murders in East Asian cities that are reminiscent of something they witnessed during the war. They suspect that the murderer is another former member of their unit, so they decide to travel overseas to hunt him down before it's too late. Unfortunately, for some of them it's already too late. Their collective past has come back to haunt them, and it becomes a race against time to save themselves.
This was a great book. Dr. Poole and the other main characters were very well-written, and I was definitely captivated by their hunt for the killer Koko. The secondary characters were also really great, including the mystical Maggie Lah and the psychotically arrogant Henry Beevers. All the characters were distinctive, and each brought his or her own special something to the story. Even the sections from Koko's perspective--though distorted--were interesting.
The plot of the novel was relatively good, following the men around both East Asia and New York City, dealing with both the trouble of the present and the ghosts of the past. However, I was a little frustrated because I figured out the twist quite a while before the main characters did, and it seemed quite obvious to me. However, the resolution of the book is satisfying, and it was a good, suspenseful read.