Polly studied faces, she wondered, she undid the disguise. But sometimes people she loved disappeared entirely, curling off like smoke. Her father, Merle, told her that her mind was like a forest, and the trees inside were her people, each leaf or needle a memory. Her mother, Jane, said that memories were the way a person tried to turn a life into a story, and Papa, Polly’s great-grandfather, said that there was a story about everything. He would tell them something long and strange to explain the existence of tigers or caves or trees, but then he’d say, Well, the Greeks said the same thing, or the Finns; the Athabascans, the Etruscans, the Utes. Days were an Aztec snake swallowing its tail, water came from a Celtic goddess’s eyes, thunder was a deadly fart from a Bantu in the sky. There was nothing new under the sun, but nothing truly repeated. Papa would row down a stretch of the Sound and back at high tide, proving his point, slipping home before it was too late to recognize home, but the water and light and noises of the world they’d left were different than the one they returned to, except for his humming, the splash of the oars, the fact of his presence.

Lately, Polly thought her mind was a river, constantly scouring and pooling, constantly disappearing, filling with details that glinted and vanished. Even as an adult, every small thing meant a little too much to her, but these days she couldn’t go on like that, because though the world had become as strange as it had been when she was a child, she could no longer indulge it. She needed to buckle down, accept some objective reality.

On June 30, a Sunday morning, Polly Schuster and her mother, Jane, were having a carefully worded argument in Livingston, Montana. Polly had smacked her head in a bicycle accident a few months earlier, and during a bumpy recovery, a long period of confusion and doubt, she’d begun to point out all sorts of things she could still remember clearly: arcane facts from college Russian history courses, lines from Othello, houses and funerals and train rides from early childhood.

“These aren’t true memories,” said Jane, reaching into the back seat to fix her granddaughter Helen’s twisted car-seat strap. Polly was backing the car out of the garage; they were off to do errands. “They’re photographs you’ve turned into memories. Ninety percent of childhood memories are pulled from photographs.”