The story begins with overheard whispers in the dark. An English girl named Bethia Mayfield, burning with secret desires, learns that Caleb, her Wampanoag Indian soul mate — and, who knows, one day, perhaps more — will be joining the Mayfield home. It’s not clear how this is supposed to work since nobody has a clue that Caleb and Bethia are even friends, much less soul mates who’ve taught each other their native tongues. And by the way, it’s pretty easy for Bethia to eavesdrop on her father and brother because the house has blankets for bedroom walls.

Perfect setup for a situation comedy, but there are no cheap laughs in this 17th-century New England. By Page 6, Bethia confesses to killing her mother, to being in Satan’s thrall, to eating forbidden fruit. She feels terrible about all that and is desperate to redeem herself, but she’s gloomy about her prospects for salvation.

Fortunately for us, she’s also a fabulously engaging narrator, nothing like the dreary Manson Girl her confessions might suggest. Bethia believes her own sins caused her mother’s fatal illness a year earlier. In addition to blaming herself for asking too many questions, Bethia regrets that she loved the natural beauty of Martha’s Vineyard too much, tripped on a hallucinogenic plant, talked back to her obnoxious brother and covertly learned Latin, Greek, Hebrew and Wampanaontoaonk. Bethia knows some would argue that she is not to blame, that Satan took advantage of a young girl, but she’ll have none of it: These are her sins alone, and because of them, her mother is dead, and Bethia is probably going to hell.

Brooks shows us the immediate and all-encompassing nature of religious belief in this world. It’s not a subject of conversation so much as the context for everything and everyone. Bethia’s very name, for example, means “God’s servant.” Recalling her afternoons with Caleb when he would instruct her about plants and animals, Bethia says, “He walked through the woods like a young Adam, naming creation.” In her eyes, Cambridge, where Caleb studies the classics and Bethia mops floors, is more or less an open sewer, while her beloved Martha’s Vineyard is an Edenic paradise, “perched at the very farthest edge of the new world, first witness to each dawn of the turning globe. I count it no strange thing that one may, in a single day, observe a sunrise out of the sea and a sunset back into it.”

The Caleb of the title is based on a real person, about whom little is known, except that he was a Wampanoag Indian and graduated from Harvard a century before the United States came into existence. Despite the title, he is not the main character and is absent for long stretches. That’s not a bad thing, because Bethia is far more interesting. Also funnier. Her passion for learning and for books is illegal and dangerous, even if the learning and books are about Christianity and her goal is to be closer to God. She sees her covert friendship with Caleb as (perhaps) part of God’s plan, yet she must lie to her family and pretty much everyone she knows. Penalties for criminal behavior in the English colonies include having a nail hammered through your tongue.