ORPHANS MAKE splendid heroes and heroines of stories for the young. Alice could hardly have journeyed through Wonderland dragging her parents behind. Dorothy in Oz thought lovingly of Aunt Min and Uncle Bill back in Kansas, but luckily for her and her readers they stayed there. Unencumbered, Dorothy relied on her own wits, ingenuity and calm courage to solve each crisis as it arose. Stuart Little is, of course, the quintessence of the theme - a very small person surviving on his own in a very large world. On a more realistic level there is Huck Finn. There was no room on his raft for a loving mother and father. I can think of a few satisfactory adventures that include Parental Guidance. Not that children want to kill off their parents. Not at all. They want to try their wings - in imagination - and find out how it feels to fly, unaided, in the adult world.

Alan, the hero of Isabelle Holland's novel, has been orphaned so many times he has nearly lost count and, as the book opens, his only emotional ties are to his animals: his dog, his cat, his gerbils, white rat and hamster. He is living in a city with an aged aunt, one of a series of relatives who have temporarily housed him. Aunt Jessie doesn't bother Alan. Her greatest virtue is that she tolerates his animals. Suddenly, and painlessly for them both, Aunt Jessie dies.

Alan faces the world alone. This causes him no dismay. What does dismay him is the certain and terrible knowledge that if adults - any adults - take over his life they will destroy his animals. It has happened before when foster homes collapsed. Kind adults found Alan a new home, but his animals - the ones he loved then - were carted off to the Animal Shelter and gassed. With Aunt Jessie, Alan rebuilt his Animal Kingdom with new pets. At her death he resolves that they will not share the fate of their predecessors.

Alan is a realist. He is not bitter, but he knows how the system works - if you are a kid and have no rights - and his sole desire is to stay out of the system's clutches. Alan knows, too, that the system does not allow boys of 12 to live alone. Therefore his primary problem is to keep his solo status a secret. This isn't easy. The most well-intentioned adults become the most threatening. Alan can evade the nasty building superintendent more readily than the concerned schoolmaster who pries into his affairs. As Alan sees the world, motives don't matter. Results matter. If either the superintendent or the schoolmaster discover his secret, the result will be the end of his beloved Kingdom.

Isabelle Holland tells Alan's story the way fantasies are best told: with simplicity and convincing detail. Alan's problems are entirely credible. His journey, alas, is not a thrilling voyage on a raft. It is a trip into today's world. His crises and hair's breadth escapes involve ringing telephones, crime in the streets and above all money. How does a 12-year-old cash a check? How does he pay a vet when his cat is sick? Because of this urgent problem Alan meets a man as isolated and as proud as himself. Thereafter the story becomes both serious and touching.

As Alan's problems multiply it becomes inevitable that he will be cornered and his Kingdom will fall. Events force him to admit emotions he has long suppressed; rage, a longing for help and companionship, even a stirring of affection and hope. When at last Alan loses his long, brave battle to fend off the entire world he finds that surrender is not quite the defeat he feared. He learns it is possible to make peace with his own species and yet not betray his Kingdom. A story that began as a fantasy of escape ends by pointing out that emotional entanglements are inescapable - and not all bad. This is an "orphan story" with an interesting twist. Alan tries his wings and crashes to earth, learning that in the real world no one flies alone.