WHERE is Aargh! and how close is it to Ugh!? What is Gar Denshed and why is Bembel Rudzuk escaping there? And who is Zormla and why is he running off with the earth's core (which has gotten dusty from rolling around on the floor) to hide it in a jar of marmalade?

For the answers, the reader may just find that, like the heroes of these books, he needs a helmet (a well-worn colander will do), a spaceship (of the 12-legged variety), and a friendly mummosaurus from Plovsnat ("the place of the chocolate cake") to fortify him with a cheese omelette before he, too, hyperjams into the delicious other worlds that Russell Hoban and Colin McNaughton have created for him here.

But for the reader to reach these other worlds, all he really needs, Hoban and McNaughton are implying, is a desire to play -- with language, people, objects, situations; with sense itself -- in order to create, however briefly, a new and personal kind of logic that is true to the vision of the players. (Hoban taps this same playful instinct, but with much more serious effect, in the creation of a new world and a new language in Riddley Walker, his recent, acclaimed novel for adults about a future, post-apocalyptic England.) Each of these small, cheerful volumes celebrates this power to transform that is particularly active in children who, like Don Quixote, can change, on a moment's notice, an ordinary something into a magical something else.

The main characters of all the books are three ruddy- cheeked, chubby brothers whose ages range from, say, 2 to 10 -- though their ages and sizes vary from book to book. Their ample, wry-humored mother (the aforementioned mummosaurus) makes key appearances in most of the books to take part in the fantasies, often affecting the direction they take and always providing the fuel to keep them going. Father has a cameo role in only one of the books -- as the mermaid king who gives the boys tape and rubber bands in The Great Gum Drop Robbery. We don't know the boys' real names, only the tags of their play personae: Zormla, Bembel Rudzuk, Navigator Blub, the baby Turpin. We never see a whole room of their comfortably over-stuffed, wildy over-decorated house; McNaughton crops his pictures to suggest the point of view of a child and to convey a sense of immediacy to the readers. For instance, we seem to crawl with the baby Turpin under the kitchen table (the bottom of the sea) when he steals the king of the desert's oasis (a laundry basket) and takes it there to eat the king's gumdrops from his first aid kit.

Hoban and McNaughton credit the reader with having an imagination that can be called upon to participate in the adventure, filling in whatever logical blanks that need to be, ignoring the extraneous. Thus, we never quite know (nor do we really need to) how we've gotten into the stories themselves. Hoban simply drops us there, without introduction or exposition, and asks us to fend for ourselves, as in the opening of The Flight of Bembel Rudzuk:

"The squidgerino squelcher was put together by the wizard Bembel Rudzuk. Bembel Rudzuk made up three jars of monster powder, then he added twelve buckets of water and Splosh! there was the squidgerino squelcher. It slobbered and it moaned, it left a loathsome track behind it. Everyone was terrified, everyone ran off and left the princess all unguarded."

Of course, Hoban does not need to explain everything because McNaughton's illustrations complement and clarify his fantasy in rich, witty detail. We see the boys' monster, a beflippered amoeboid mass in a fabric that looks like a striped awning, and it is spraying gallons of water onto the floor as it circles "the princess" (guess who?) while she is standing on a kitchen stool, obviously reaching for something from a high back shelf. Without skipping a beat, she asks the two-boy creature, "Where'd this monster come from? And who's going to clean up after it?" The boys must find Bembel and clean up the puddles before the princess returns from her shopping, and they do, but not before they also find a cheesecake that's cooling on a rack in the Gar Denshed (get it?) and help themselves to samples which they cut from the cake with a saw.

Still managing to stay in character, Mom (er, the princess) brings in the decimated cheesecake to give the boys a slice with their hard-earned cocoa and asks Bembel and the monster if they think that perhaps mice have been munching on it. Hoban ends the book on a wonderful note, in complete harmony with McNaughton's robust pictures, by having the boys confess by completing the joke she's begun. They answer her, without guilt or fear of punishment, squeaking out of sheer delight -- because of her loving indulgence, their own inspired stroke of wit, and the utterly satisfying way this chapter of their ongoing game has been played.

While two of the books are literally surging with energy and thus stand out for me as better (Bembel Rudzuk and the first of the series, They Came From Aargh! -- the latter published last year), I recommend all of them highly. Clearly, Hoban and McNaughton respect the child reader and the spirit of play that animates him. At the same time, they acknowledge that there can be problems when the play goes too far, spilling over onto someone else's floor. Yet parents and children are not made into adversaries in order to resolve these difficulties, and the fantasies that they have created togther do not have to be denied or destroyed in order to settle differences. Instead, Hoban and McNaughton show the reader just how vital it is to preserve the fantasy -- not as an escape from reality but as a means for solving problems, preserving dignity, and cementing love between the players. The fantasies keep bubbling up, irrepressibly, in these stories, like the casseroles, pizzas, or cakes that mom keeps bringing out. And, like the boys, I want to cheer them, these hearty, human dishes.