The voice of Caleb's Crossing belongs to Bethia Mayfield, growing up on a tiny island settlement of Great Harbor amid a small band of pioneering English Puritans. Possessed of a restless spirit and a curious mind, Bethia slips the bounds of her rigid society to explore the island's glistening beaches and observe its native inhabitants. At twelve, and the two forge a secret bond that draws each into the alien world of the other. Bethia's father is Great Harbor's minister who feels called to convert the Wampanoag to his own strict Calvinism. He awakens the wrath of the medicine men, against whose magic he must test his faith in a high-stakes battle that may cost his life and his very soul. Caleb becomes a prize in this contest between old ways and new, eventually taking his place at Harvard, studying Latin and Greek alongside the sons of the colonial elite. Bethia also finds herself in Cambridge at the behest of her imperious elder brother. As she fights for a voice in a society that requires her silence, she also becomes entangled in Caleb's struggle to navigate the intellectual and cultural shoals that divide their two cultures.