In the spring of 1974, Calliope Stephanides, a student at a girls' school in Grosse Pointe, finds herself drawn to a chain-smoking, strawberry-blond classmate with a gift for acting. The passion that furtively develops between them leads Callie to suspect that she is not like other girls. In fact, Callie has inherited a rare genetic mutation. The biological trace of a guilty secret, this gene has followed her grandparents from the crumbling Ottoman Empire to Detroit and has outlasted the glory days of the Motor City, the race riots of 1967, and the family's second migration, into the foreign country known as suburbia. Thanks to the gene, Callie is part girl, part boy. And even though the gene's epic travels have ended, her own odyssey has only begun.