Berkeley, Calif. ? At age 39, author Michael Chabon appears well placed in the great, grown-up world. He is married, has three children and lives on a leafy side street in a scenic, high-priced city.

But once he steps inside the cottage behind his house, time rewinds. Old baseball photos and sketches of cartoon heroes cover the walls and a turntable sits near his computer. The cottage serves as his office, but it could be mistaken for a reconstructed clubhouse.

“I definitely have a few toys up here,” he says with a laugh during a recent interview. “To me, it’s like Superman’s fortress of solitude or the bat cave, a place where trophies of my various campaigns are kept.”

Winner of the 2000 Pulitzer Prize for “The Amazing Adventures of Kavalier & Clay,” Chabon receives seven-figure advances for his books and got comparable money for a “Kavalier & Clay” screenplay, to be produced by Scott Rudin of “Addams Family” fame.

He is working on a novel, set in Alaska, but home life directed him to an additional project. Reading “Charlotte’s Web” and other classics to his kids made him want to write a children’s book himself.

“Summerland” is a 490-page tale of environmental peril and old-fashioned Americana, with such favored Chabon themes as baseball, superheroes, fathers and, curiously, failure. Miramax Books is giving the fantasy novel a first printing of 200,000, and has already signed up Chabon for two sequels.

“I have big hopes for ‘Summerland,”‘ says Joe Monti, the children’s book buyer for Barnes & Noble Inc. “You can tell that he understands children’s literature. He’s not just doing it on a whim, or following a trend. He’s quite serious about it.”

The hero of “Summerland,” 12-year-old Ethan Feld, is billed by Chabon as “The Worst Ballplayer in the History of Clam Island.” Banished to baseball’s version of Siberia deep right field Ethan is so hopeless a hitter that he never lifts the bat from his shoulder. The boy “was mortally afraid of striking out swinging,” Chabon writes. “Was there any worse kind of failure than that? Striking out.”

Chabon’s sensitivity to failure well documented in the novel “Wonder Boys” should by now be well exorcised. But like a self-made millionaire ever afraid of losing his fortune, Chabon identifies with what can go wrong, citing parenthood as an ongoing reminder.

“Being a good father is probably my major ambition in life,” he says, “and yet I think there’s not a day that goes by that I don’t feel I failed in some way or another. I didn’t pay attention when I should have paid attention. I missed a cue my kid was giving me and there was a problem to deal with. It’s just an endless failure.”