John Connolly was already several books into his bestselling series starring Maine private detective Charlie Parker when a few thoughts occurred to him.

One was that his literate, hardboiled novels were dabbling increasingly in the supernatural. More than that, somehow, Connolly had developed a layered story arc involving a mythology of fallen angels in a timeless morality play - and, yes, a melancholy hero so complex that members from both sides of the Good/Evil construct aren't exactly sure whose side Parker is on.

This ambiguity reaches astounding levels of imagination and suspense in "The Wrath of Angels" (Atria, 474 pages, $26), the just-published 11th book in the Parker canon. In it, the hero must go deep into a creepy stretch of Maine woods that defies the laws of nature, hoping to find the remains of a crashed airplane that contains a list of citizens who have made the sort of contractual deals previously associated with Robert Johnson and Dr. Faustus.

The narrative journey also meanders through locales in New York, Massachusetts and Connecticut. Along for the ride are Parker's loyal but criminally enthusiastic pals Louis and Angel, as well as the enigmatic Collector - a one-man judge/jury/executioner who operates according to his own murky moral flowchart.

Oh, and lest ye fear that otherworldly and maleficent beings might be in short supply since, in an earlier work, Parker killed off Brightwell - one of the spookiest crime-fiction villains ever - rest assured that other resolutely sinister figures are searching for the same devil's list. (Hint: What's to be said about an instinctively malevolent silent child who seems to remember his own death? A lot, actually.)

Over the course of the book, several previous thematic threads are followed and unraveled - just as Parker inevitably stumbles into many new and unpleasant situations.

In a phone conversation earlier this week from his native Dublin - Connolly also owns a home in Portland, Me. - the author clearly enjoys the hell out of the mess he's created.

"At the start, it never occurred to me to create a story arc," he laughs. "I'd sold the first two books and never thought beyond that. I was still in fear the publisher would say, 'This Charlie Parker was a horrible idea. Keep your advance money, but go away and don't write anymore.'"

Instead, Parker became a bestselling concept and Connolly began to breathe a little easier and think of a bigger narrative picture. Still, despite the requisite introduction of recurring support characters and the real-time development of Parker and his on- (and off-) going personal relationships, it wasn't until the fifth book in the series, "The Black Angel," that Connolly realized that a huge backstory and mythology were evolving.

"I'm a hopeless planner; I can't plan anything," Connolly says, describing for example that morning's domestic situation: his wife was out and, having to nuance both kids and pets, the writer was completely befuddled. "I'm that way with the writing, too. I can't plan what happens with each book. But it also became obvious that there were more and more points that were starting to connect."

What happened, he explains, is that after several Parker thrillers, he took a few years to write some short stories and a few stand-alone novels. When he returned to the series to write "The Black Angel," a new awareness took over.

"With writing in general, even if you're not working on something, you're thinking about writing," Connolly says. "I'm not one of those guys who believes that the act of writing is channeling some creative gift, but I do think, all along, your subconscious is doing some work for you. And, yes, I began to see the bigger picture, if you will, or the overall story arc."

By design, Connolly varies how much any given Parker mystery falls into the cobweb of the mythology. Some of the books are more conventional PI stories; others, like "The Wrath of Angels," are resolutely intertwined within the fallen angel framework.

"I try to balance the Parkers that focus on the larger story arc with the ones that don't," Connolly says. "Publishers like the more stand-alone aspect because they don't discourage first-time readers who might come along eight books in and have no idea what's happening."

Not only is "The Wrath of Angels" decidedly one of the stories heavily involved in the mythology, it's fair to say it might be thought of as a connective follow-up to "The Black Angel" - even though other Parker titles have been published between the two.

"Yeah, the new one is a kind of quasi-sequel to 'The Black Angel,'" he says. "Part of the fun is that, in this one, I'm crossing a bit of a line, and I knew it was going to be tough because I'm bringing back (a character) who was dead. The challenge, then, is to see how far you can push the reader's credulity without buckling."

All told, the whole Parker saga presents quite a balancing act for Connolly - although he obviously loves it.

"I don't want to play a teasing game, and I respect and appreciate my readers," he says. "They seem to like the mythology but, at the same time, you can sense they want a conclusion to the conflict. I say, be careful what you ask for. Do you really want it to end? At the same time, mine is a benevolent dictatorship. I write what I write, and it's in the job description that you have no business pandering to the reader."