In the slim “American Taliban: A Novel” (Random House, 272 pages), Pearl Abraham traces the path of a sweet, upper-middle-class kid from surfer dude to American Taliban.

John Jude Parish is loosely modeled on John Walker Lindh, who was captured just after the start of the U.S. war in Afghanistan, and whose comfortable background provoked as much anger in this country as his actions.

But “American Taliban” is clearly a work of the imagination, taking the outlines of a true story and creating something else. Abraham sets herself a real challenge: Most readers aren’t going to approach this novel with a lot of sympathy for a young man — even an innocent, endearing one — who falls in with people who attack this country. Yet she does manage to draw a character who evokes sympathy, even as he drifts from inexplicable situations into unconscionable ones.

And it’s always tricky to make these improbable transformations believable. A good writer has to make the changes gradual yet inevitable — make it clear why this particular person took a wrong turn and couldn’t right himself.

Abraham deftly strews John’s path to disaster with challenges he could meet, but doesn’t. As you read, you think: Is this the turning point? Is this? The skateboarding accident that landed John in the hospital? Studying religion at a sharia school rather than at college? Spending a summer in Pakistan? Encountering 12-year-olds in Peshawar who had been blinded at a bomb-making retreat? But of course, they’re all turning points. And of course, John is blind to their significance, and to the chance they offer to take charge of his life’s direction.

John’s spiritual journey takes some inspiration from Sir Richard Francis Burton, who had “lived the life of a nineteenth-century adventurer, but he’d also penetrated the ancient wisdom of secret worlds. Which John wanted. Both the physical and spiritual experiences.”

The problem is, John isn’t the tough-minded adventurer that Burton was. He’s so naive — and passive — that he lets the waves of history carry him to the next place. And whatever happens, happens.

If John had stayed in the kind of life his parents had envisioned — Brown University, some travel or volunteer work, then a profession — he probably would have been fine.

That’s one of the most interesting questions “American Taliban” raises: Can parents rear their children in all the right ways for the lives they imagine for the children, and yet leave them unprepared when the path veers unpredictably?

In many ways, Bill and Barbara Parish did a great job bringing John up. He’s genuinely decent and caring, bright, and interested in other cultures and in people who aren’t exactly like him.

And John’s attraction to Islam is real: In Islamabad, he answers the call to prayer and feels that “he was alive. His voice hummed with the hum, and dissolved into the bluing air and brightening sky as one voice. And then, all together, all at once, he and these thousands, these thousands plus one, rocked back on their heels, and turned their heads to the right, turned their heads to the left, and acknowledged one another in their descent back to ordinary life. …”

Because the roles of Bill, and especially Barbara, are such a subtle subtext in the novel, it’s easy to see the ending initially as evidence that Abraham couldn’t think of a way to wrap up her story.

But on reflection, the conclusion seems much more like an act that’s both unsettling and a gesture of real empathy.