As bedtime books go, Goodnight Moon by Margaret Wise Brown, illustrated by Clement Hurd (HarperCollins, 1947), remains one of the gold standards. But author/illustrator Michael Rex thought the classic tale could use a healthy dose of spookiness, so he set to creating Goodnight Goon: A Petrifying Parody (Putnam). Apparently, plenty of parents and kids were ready to follow Rex down the parody path, because the book has hit bestseller lists and now has 100,000 copies in print, since its August publication.

In Rex’s gently creepy version, Brown’s cozy green room gives way to a cold gray tomb and black lagoon—the perfect setting for young monsters being tucked in. According to Timothy Travaglini, senior editor at Putnam, the project had been brewing since the mid 1990s, when Travaglini was at Henry Holt, where Rex’s earlier picture books (My Freight Train; The Painting Gorilla) were published.

“In 2000, Mike told me of this idea he had to retell Goodnight Moon, but with monsters,” Travaglini says. “We were both inspired by Charles Addams’s single illustration of the nursery rhyme ‘Wee Willie Winkie.’ ” But Rex was hesitant to be seen as disrespectful toward the iconic picture book. “I think he had visions of children’s librarians decked out like villagers with torches and pitchforks intent on running him off the edge of a cliff.”

Travaglini loved the idea and made a point of asking Rex about it periodically. “It was not until five years later, when I had finally landed at G. P. Putnam’s Sons that we signed the book up,” Travaglini says. “And from there it was yet another three years for Goodnight Goon to finally become a book.”

Based on feedback thus far, the book has been a draw for devoted fans of Brown and Hurd, as well as for newcomers. “Certain original works are so well-crafted, so perfect in their appeal, that they lend themselves to an infinite variety of retellings,” Travaglini explains. He says that while the parody is good fun, Rex’s work is “not intended to be a joke, nor is it intended to poke fun at” Goodnight Moon. Both author and editor believe it’s an homage that stands on its own.

At Vroman’s Bookstore in Pasadena, Calif., bookseller Steven Ross has enjoyed using the book at preschool storytimes (where he’s better known as “Mr. Steve”). “I tried a dry run for storytime, reading Goodnight Goon, but not including the original. The kids thought it was funny,” Ross notes. “But when I read Goodnight Moon near the beginning of storytime and then Goodnight Goon at the end, they really got it—and thought Goon was hilarious.” The book was a huge hit at the store’s Halloween celebration and storytime last week, too.

Kris Vreeland, children’s department manager and book buyer, reports that Vroman’s two locations have sold more than 75 copies of Goodnight Goon to date. “It’s just good fun,” she says. “And reminiscent of something we all knew as children. Rex put a cute twist on it, and it’s not too scary.”

After having such success with one Brown parody, another is not far behind. Rex will serve up The Runaway Mummy (a riff on The Runaway Bunny) next spring. And for those who can’t get enough of the mini-genre, Little, Brown published the politically flavored Goodnight Bush by Gan Golan and Erich Origen last May.