Calvin Wideman, a former evangelical Christian, shed the religious beliefs his parents taught him but not his faith in seeking truth, love, and a higher purpose. His coming-of-age story begins the weekend before Christmas 1974. Flying back to Chicago, he feels homesick for Mexico, the country he spent his savings wandering as a gringo hippie peasant. His best friend Josh meets him at O'Hare in the wee hours of Sunday morning, apparently to gloat that Cal will finally have to deal with so-called real life. Josh urges him to phone his mom who has been pestering with calls about some "urgent family matter."

Cal's parents inform him that his younger sister Rachel has joined a cult. He suspects they're overreacting but agrees to act as their emissary and the next day visits the alleged commune in an ultra-rich suburb. He receives a polite welcome and learns more than he ever wanted to about the group's radical reinterpretation of the Greek New Testament. On Christmas Eve, Cal finds himself playing devil's advocate to defend Rachel's new beliefs to his parents. Their militant opposition mystifies him because it blatantly contradicts precepts that are fundamental to their Reformed theology. The drama that ensues forces Cal to relive the trauma of losing his religion and, at the same time, to navigate the inevitable tensions between faith and reason, freedom and family, memory and conscience, the world as we find it and the world as we want it to be.