It deals with the mysterious death of former state trooper Ronda Reynolds.
The unsolved case was also a KOMO 4 Problem Solver investigation.
"I just knew that one day I would write this book," said Rule during an exclusive interview with KOMO News. Rule said when Reynolds was found dead in her home of a gunshot wound shortly before Christmas 1998, she had an immediate gut reaction.
"Something was hinky; it just didn't make sense," she said.
The Lewis County coroner ruled it a suicide. But just as Ronda's mother, Barb Thompson, couldn't let that stand, neither could Rule.
"I think a lot of it was because I was a cop and she was a cop, and there was that kinship. I had daughters the same age," she said. "So it was always there waiting for me, and I just, you know, maybe because I'm older, maybe it's because this is my 31st book, but it was time."
So nearly 12 years later, inside the pages of Rule's latest true crime expose, Reynolds' story has come alive.
"There are many likely suspects in this case," said Rule, "many, that some people may not have thought of."
Two years ago, KOMO News also investigated Reynolds' death. We conducted firearms tests with the help of expert Marty Hayes. We talked to forensic pathologist Dr. Jeffrey Reynolds and former detective Jerry Berry. All concluded Reynolds did not commit suicide. Rule agreed. When asked if she believes this is a murder case? Rule said, unequivocally, "Oh, there's no question."
"In the Still of the Night" is a departure for Rule. Unlike most of her true crime books, there's been no criminal charges, no criminal trial. But there was a civil trial last year to determine how Reynolds died. The jury decided unanimously Wilson was dead wrong; Reynolds did not commit suicide.
The evidence in that trial gave Rule the framework she needed to publish a crime story without a guilty verdict. When asked how she writes around the fact that there's no definitive end to this case, Rule smiled and said, "Well, I think there is an end. And when you get to the end, call me up and tell me what you think."
See, Rule's quest for information didn't stop with the trial.
"Thank God for people who were brave enough to come forward," said Rule, who, along with Reynold's mother, continued to turn up new information. "So these are things the killer or killers never took into ... I don't think they even knew about them."
Rule believes information in her book will ultimately lead to an arrest, or arrests. Because of that, her family didn't want her to write this story. "
"It's a dicey thing to write. There are people out there who are guilty of murder," she said. But Rule is committed to telling this story. "The main purpose is to find someone - to identify someone - who got away with murder."
With that in mind, Rule has also established a reward fund of more than $30,000 for information leading to the arrest and conviction of the killer. Then she'll have a new ending when the book comes out in paperback.