Somewhere within the American consciousness lies the myth of escape - the promise that if things get worse we can always light out for new territory. One version or another of this primal urge gives substance to the work of nearly all major American novelists. It also helped to populate US cities, settle California, and put the first man into space.
A thin line separates the escape from the quest. When Huck Finn boards the raft, for instance, is he running from Pap and civilization, or in pursuit of freedom and dignity? Was our great migration across the continent a getting away or a moving toward?
Similar tensions have peppered both the fiction and the nonfiction of Paul Theroux, whose travelogue ''The Great Train Bazaar'' made him a major author back in 1975. In ''The Mosquito Coast'' he returns to that dilemma so central to our experience: Are we the driven or the driver?
In this case the person asking the question is Father, who first appears as a kind of gentle lunatic bent on moving his family from a farm in Massachusetts to the deep interiors of Honduras. ''I'm the last man, Charlie!'' he boasts to his son, the 14-year-old narrator of the story. Driven by a bitter reaction to everything around him, he refers to himself later as ''the vanishing American,'' and to prove the accuracy of his increasing arrogance he forces his family into a primitive subservience that almost costs them their lives.
Much of Father's ranting is played out on familiar literary ground, and Theroux is scrupulous in supplying references to earlier narratives. The family compares itself to Robinson Crusoe and the Swiss Family Robinson. Someone calls up ''Lord of the Flies.'' But the two books most clearly antecedent are left unmentioned. One is ''Heart of Darkness,'' with its patterned layers of imagery and brooding drive toward the center of madness. The other is ''Moby Dick,'' dominated by a raving Captain Ahab, whose curses hurled at God are echoed in Father's fierce independence and determination to take everyone down with him.
For a time Father is only disquieted by the imperfections of the world around him: ''If God hadn't rested on the seventh day, He might have finished the job.'' But eventually he becomes enraged at the colossal failure of his design to improve on nature and man. And at last, with frightened self-recognition, he is forced to embrace the vultures that have circled him throughout his obsessive venture.
This is a chilling yarn of survival, and, like Ishmael, Charlie comes back to tell the tale with the shrewd detachment of a seasoned observer. Theroux allows him to grow in his understanding of certain moral implications, but the author never loses his tight grasp on the lines of suspense.
No easy conclusions settle the issue of escape vs. quest; in good fiction they seldom do. Theroux brings together, instead, the dramatic conflicts that govern human nature; we then decide for ourselves what order they suggest and slip into place the puzzle's final solution. Theroux's willingness to trust the reader is one reason his impressive string of books continues to move toward the wholeness of myth.