Nightingale in a Cage : HAROUN AND THE SEA OF STORIES <i> By Salman Rushdie (Viking: $18.95; 210 pp.) </i>

This is a book in captivity; marked by it, marred by it, and owing its own odd value to it.

Salman Rushdie, still in hiding in Britain from the death sentence pronounced by the Ayatollah Khomeini--whose curse failed to expire with him--gives his pain the shape of a children’s story. It is not a real children’s story, or if it is, it is not a very good one. It is not really a good story of any kind; certainly nowhere near the quality of “Midnight’s Children,” or of the book that imprisoned its author: “The Satanic Verses.”

What it is, in its own way, is a prison document, and unexpectedly touching. Rushdie has written a fable about the kind of tyranny he is suffering from, one which seeks to cripple the Word. It is partly crippled itself. From a dancer confined to cramped movements in a cell, we learn two things: What a crime it is to confine a dancer; and what a dance looks like when deprived of what it requires to move, though not of what moves it in the first place.

“Haroun and the Sea of Stories” began as a bedtime story for Rushdie’s son, Zafar, according to a publisher’s note. It evolved into the voice of a man ostensibly performing for a child, but crying out, in fact, to the grown-up world outside.

It tells of the storyteller Rashid, a bubbly fabulist in a nameless sad city, who loses his gift when his wife runs off with an accountant. Rashid had been hooked up to the Sea of Stories--hence, his abilities--but through a bureaucratic mix-up, his invisible faucet is to be cut off. Haroun, his son, catches a Water Genie in the act of disconnecting it. After some argument and a trick or two, the Genie agrees to take them to headquarters, run by a figure called Walrus.

Walrus headquarters, and the Sea of Stories, are on a moon named Kahina. Rashid, Haroun and the Genie travel there on the back of a clockwork hoopoe bird. When they arrive, they find that Kahina is in crisis.

The Sea of Stories is being polluted by the evil Khattam-Shud, ruler of Chub on the dark side of the moon. After a series of adventures, Haroun, Rashid and the Walrus Army destroy Khattam, along with his factory-ship that is pouring poison into the sea. Stories will go on, unpolluted, and Rashid will get his wife back.

Rushdie, whose gifts include wit and wildness in a sharp engagement with the world’s complexities, has trouble applying these talents to the style of a children’s story. There is humor in “Haroun” but there are also disabling quantities of whimsy.

Rashid’s sad city, we are told, borders on “a mournful sea full of glumfish which were so miserable to eat that they made people belch with melancholy.” When Haroun suffers from a loss of concentration after his mother runs away, a neighbor opines: “Cause is located in his pussy-Collar-jee.” The talkative hoopoe bird prefaces his speeches with “But . . . But . . . But.” His name, of course, is Butt. Whimsical capitalization--”Too Complicated To Explain,” for example--has echoes of “Winnie the Pooh”; the impatient creatures who conduct the bewildered Haroun on his adventures recall “Alice.”

Rushdie fabricates the outlandish denizens of Kahina and the twists and turns of the story in a hurried, piled-on fashion. He forces things; he lacks the belief and gravity that a good children’s story requires for its fantasy. Rushdie is interested in something else.

The something else is his protest against oppression. And if the whimsical images of “Haroun” can set the reader’s teeth on edge, they take on a different aspect insofar as they transmit a message.

Rashid, the storyteller, is Rushdie’s free artist. His dependence on the Sea of Stories says that art is not arbitrary and self-willed, but that it draws on the wellsprings of human need, and that it is as essential as water.

Khattam-Shud, of course (it means “over and done with” in Hindustani), is a Khomeini. In an encounter with Haroun, he concedes that stories may be fun, but that life is not about fun but about control. And since stories--art--subvert control, they must be destroyed.

And Rushdie will give his fable a further turn, subtle and affecting. The Walrus and his organization, working to keep the Sea of Stories fresh and pure, had arranged to stop the moon’s revolutions so that their Sea would always be in the sunlight. This meant, though, that Chub was always in the dark. Khattam thrives on darkness; his destruction is accomplished when Haroun arranges to get the moon turning so that sunlight hits Chub, as well.

If a Khomeini can come to power, it is in part because the West has arrogated sunlight to itself, and left much of the globe bereft of it. Rushdie defies the Ayatollah’s curse. It is he, not his persecutor, who is the true defender of the Third World.

Rushdie employs the style of a children’s story with a trying self-indulgence. But he uses it to say something that is grave and moving, both in its wider reach, and when applied to his particular circumstances. We notice, for instance, his images of unconfined movement--a bus rocketing along, the soaring hoopoe bird--that this confined man uses to sustain his spirit. And awkwardness becomes its own art in the dedication verse that cites other fantasy kingdoms:

Zembla, Zenda, Xanadu:

All our dream-world may come true.

Fairy lands are fearsome too.

As I wander far from view

Read, and bring me home to you.

Rushdie had all the time in the world to work the first letter of each line into an acrostic of his son’s name. That incarcerated time weighs upon all of us; it recalls another two lines. Blake’s:

A nightingale in a cage

Puts all Heaven in a rage.