Something awful happened every year on the river. How could it not? Even during a spring when the flow wasn’t record-breaking, whole trees shot down like Pooh sticks. A stiff dead baby bison had floated through town a few years earlier with its own golden eagle riding on top, watching the world between nibbles.

People loved the river Yellowstone for coolness, prettiness, peace, food, wildness, a dare, but touching it meant buying a lottery ticket. Using it was like driving on ice, flying a small plane, walking out of a bar with a stranger. It was easier if the unlucky person was a tourist, but usually it was someone the town knew, someone who loved the river, who understood what he or she might be getting into. This year it was Ariel, who’d been born here, played soccer and cello, tested high, been generally beloved.

When Polly and Ned moved to Livingston, Ariel, age seven, was one of the first people they met. Harry, Ariel’s almost stepfather for three years before Ariel’s mother found religion, stayed close with the girl and brought her to Polly and Ned’s ramshackle house while they renovated, and Ariel swept sawdust or played with paint samples. When Ariel’s mother married the next year, they saw less of her, though Harry kept up monthly lunches. Ariel’s stepfather, who worked for UPS, was a conservative Christian and loved his stepdaughter but was jealous of his wife’s history. Harry, who’d managed the impossible task of being a popular cop in a small town, was a difficult predecessor.

Ariel started helping with Sam when she was fifteen and he was two. She succeeded her joyless best friend Connie Tuttwilliger, whom Polly used for a few hours a week when Sam reached two months. Polly had been finishing a cookbook edit, and her notion of how things would proceed—she’d work at night and during the baby’s naps, or perhaps while Sam was peacefully watching dust motes and attentive dogs—was shredded during the first weeks of colic and doubt and fatigue. Connie thought Polly and Ned were bizarre—so many books, wine bottles, the foreign and violently flavored condiments in the refrigerator, and the clean counter of cooks above an unclean floor of slobs—and was offended by the idea that Polly insisted on nursing rather than handing over the baby for a bottle. Connie generally lacked humor, or what Ned referred to as elasticity, but she was renowned for her first aid skills—when Bobby Lundquist had stuck his tongue in an outlet, she’d gotten his heart beating again, and this had made her services priceless to all the parents who signed up for her summer swimming lessons. She was in demand, and the Berrigans were relieved when Ariel, who was more their speed, was allowed to babysit despite their status as nonbelievers.