The Worms in Castro’s Apple : LOS GUSANOS, <i> By John Sayles (HarperCollins: $22.95; 475 pp.)</i>

All Marta de la Pena needs is wings to fly. She is already half-angel, with eyes that see into men’s souls. She is a modern-day Joan of Arc, with a plan, if not to liberate Cuba, at least to let Fidel Castro know that there still are people willing to fight for their lost island.

Marta is the central force unifying John Sayles’ collection of Cuban dreamers, “Los Gusanos”--the worms, as Castro branded those who fled his revolution. The time is 1981, the place Miami.

Marta’s plan is to blow up the power station at Cuba’s Playa Giron, the same mission that killed her brother Ambrosio 20 years before in the Bay of Pigs invasion. She reads her dead brother’s secret war diary over and over, but misinformation abounds there as it did during the invasion, as it does daily in the streets of Miami’s Little Havana.

Twenty years before, Marta’s father was a proud landlord of a ranch outside Camaguey. He kept a bull who “had a thing like a strong man’s arm and could break the back of a young heifer.” But the bull was all power and no seed for the future--a strong metaphor for weighty dreams.

Scipio de la Pena is now aphasic in a nursing home, speaking to his daughter without words. Marta lives with her mother, a woman who measures her life by how much her family eats.

Scipio’s brother, Felix, is the second son from a time where privilege went to the firstborn. Tio Felix is a man constantly at ends to prove himself as “El Segundo.” Tio Felix is one of the chosen few that Marta has gathered for her mission.

Also chosen in Marta’s plan is Padre Martin, a defrocked Catholic priest who is a manager in a grocery store. His collar was taken from him years ago for preaching Cuban politics from the pulpit in Miami.

“El Halcon” is a torturer from Batista’s regime who now runs a motel where rooms can be rented by the hour. He’s also a professional hit man. The only reason he’s avoided American jails is his work as an informant for the CIA. He will supply the heavy artillery for Marta’s invasion scheme with the stipulation that he is included in the plans, the better to inform his CIA contact.

Central Intelligence Agent Walt’s kidneys are shot by years of Cuban coffee and rum-laced Cokes. He spends his time wondering if he can receive workmen’s comp for his ailments while keeping a tired eye on any new invasion plans brewing in Miami.

Dewey is another of Marta’s chosen--a 16-year-old high school dropout who works as an orderly in the nursing home where Scipio de la Pena is dying. Dewey sports a neo-Nazi hairdo, and his knowledge of firearms is frightening, given his daily fantasies of exterminating anyone who angers him, including the mice in his South Beach room.

That’s only part of the cast of characters on this side of the Florida Straits. On the island of Cuba there is another cast, past and present, including two neighbors on patrol at Playa Giron: a young boy who dreams of becoming an engineer, and an old man whose seven daughters died of infant dehydration before Castro’s health clinics and whose son dies in Angola during Castro’s African Vietnam.

It is to Sayles’ great credit that he delves beneath the surface of history in private lives and unspoken motives. He doesn’t take the easy way out. One generation warns the next not to ask too many questions when fighting Castro. And while the next generation knows they don’t want to fight where questions aren’t welcome, they fight anyway.

The Cuban war, from the revolution to the Bay of Pigs to plots hatched weekly in Little Havana, isn’t as simple as the Communists versus Los Gusanos. It’s a war of factions on both sides, each with its own confusion of rumors and each “tending a private garden of mistrust.” There are rich Cubans who want their land, rich Yanquis who want their sugar, Fidelistas betrayed by Fidel, followers of Batista betrayed by greed, and innocents, free of history, betrayed by their lack of history. “A spy among Cubans is anyone with ears,” one rebel states. “In Europe, monks take a vow of silence, but in Cuba, they only promise not to shout.”

Sayles’ battle scenes are frightening and sensual. He leaves no doubt that here is where blood, not rumor, not idealism, is shed. And his prose soars in the private battle of men’s souls seeking survival in places that bodies weren’t meant to survive.

The story of a raft ride from Cuba to the United States, told by a Bay of Pigs veteran, is such a jewel: “Time seemed to refuse to pass, only to bake into their skin, to rock them gently to nowhere.” Announces one of the rafters: “I’m bored, somebody drink seawater and go crazy.” Eight men, followed by two sharks, start the journey. Only one survives.

The prison passage of Villas (one of Marta’s chosen who declines the honor) is another such gem. In solitary confinement for three months, the former history professor decides that if he can put himself into a routine of his own making he will be his own prisoner, not theirs. And so he divides the four corners of his tiny cell into a universe: Isles of Pines, Gibara, Santiago and La Habana; divides the darkness into time; divides his time into forced marches, three paces one way, four diagonally across. He delivers grand history lectures in the morning and afternoon, playing the part of students and teacher.

But Sayles’ writing is too often difficult and crowded. The very frequent use of untranslated Spanish, varying in length and complexity, is a constant stutter in a style that is more visual than rhythmic.

“Los Gusanos” supports a rich cast of characters, but in the end they far outweigh the plot, which gets lost as high concept. The well-researched history becomes didactic in the mouths of nursing-home patients. Marta’s plan becomes little more than a gathering of people and arms. Does she know how to shoot a gun? Is there no physical training for this mystical being?

Marta gains more as a symbol and less as a person as the book progresses: “(men) drawn by her beauty . . . caught in the challenge of unlocking her secrets. . . . Proud men discovering their own vanity under her gaze.”

Too many mysteries are left unresolved, including the murder of a young boy on the streets of Little Havana, an incident that opens the novel. Too much time and energy is spent on people and places, past and present, that have little or nothing to do with Marta’s vision. But when the book delivers, it’s with strong punch and well-placed irony:

During university riots in Cuba, a taxi driver asks a student if Batista is dead. The student, bleeding profusely from an angry hole of a gunshot wound, answers, “I don’t know. I didn’t reach the palace.”

“I’ve never been inside myself,” muses the taxi driver. “They say it’s a wonderful building.”