("Heat Wave" by Richard Castle, Hyperion, 196 pages, $19.99).

Art may imitate life and vice versa. But how about art imitating TV and then becoming a best-selling mystery?

As in "Heat Wave," which is so hot it has sold out at local bookstores. The book is now in its fifth printing, according to Marie Coolman, executive director of publicity for Hyperion Books, and more copies will ship to distributors on Nov. 9.

The novel was part of the plot of ABC's "Castle." Richard Castle, played by Nathan Fillion of "Firefly" fame, is a rich and successful mystery writer who is shadowing New York homicide Detective Kate Beckett (played by Stana Katic), in order to write a new series. His "Heat Wave" was an instant best-seller on the TV series and a recent episode included a book signing.

Well, someone also made the real-world book a fun, entertaining mystery and a hit at the bookstores. "Heat Wave" debuted at No. 10 on the Publishers Weekly list two weeks ago and jumped to No. 6 last week.

So who's the real author?

Since mystery writers James Patterson, Michael Connelly and Stephen J. Cannell have appeared as guests on the Monday night TV series, their names have been mentioned on fan Web sites. Coolman of Hyperion said Nov. 6 that "the author has appeared on an episode of "Castle."

Hmmmm?

And the book is a good read. It's funny. It's tense. The mystery is well done and the emotional connections are deeper than the TV series.

In the book, NYPD homicide detective Nikki Heat investigates the death of a real estate tycoon who is tossed off the sixth-floor balcony of his luxury home during a heat wave in New York City. Detective Heat is being shadowed by magazine reporter Jameson Rook, a name-dropping, wise-cracking Pulitzer winner. Sound familiar?

"Heat Wave" is a mirror version of "Castle," only racier, say, if the ABC show aired on Showtime.

And the book has enough twists to keep whodunit fans entertained. In the most tense moment of the book, Nikki Heat barely escapes an attack by a killer in her apartment. The action picks up as more bodies are found, all related to the tycoon's death.

And like the TV show, the humor remains throughout. Reporter Rook brings Detective Heat a nonfat, no-foam, double-pump vanilla latte.

"You know how I feel about frou-frou coffees," she says.

He responds: "And yet you have one every morning. Such a complex woman."

At the end of the book, only one question remains: Who's the real author? That's still the biggest mystery.

Reach George Wright at 473-7321 or gwright@journalstar.com.