On December 1, 1946, Paula Jean Welden put on a bright red parka, left her Bennington college dorm for a hike, and vanished. Eighteen, white, blonde, wealthy; her story captivated a nation, but she was never found.Each chapter of Quantum Girl Theory imagines a life Paula Jean Welden may have lived after she left that room: in love with a woman in a Communist cell and running from her blackmailer in 1950s New York. A literary forger on the verge of discovery at the advent of the computer age. A disgraced showgirl returning home to her mother's deathbed. Is she a lobotomy victim, is she faking amnesia, is she already buried in the nearby woods? Or is she Mary Garrett, the hard-edged clairvoyant running from her past and her own lost love by searching for missing girls in the Jim Crow south? A trip to Elizabethtown, North Carolina, leads Mary to a twisty case that no one, not even the missing girl's mother, wants her to solve. There, Mary stumbles into an even bigger mystery: two other missing girls, both black, whose disappearances are studiously ignored by the overbearing sheriff. Mary's got no one else to trust, and as her own past tangles with the present, it's unclear whether she can even trust herself. This brilliant jigsaw puzzle of a novel springs off from a fascinating true story to explore the phenomenon of "the missing girl": when a girl goes missing, does she become everyone people imagine her to be?