The third child in a family that wanted only two, Muriel Sullivant has always been the outsider. Single, twenty-three, shes living in a New York City rent-stabilized walk-up, a birds nest of an apartment outfitted as much by serendipity as by intent: note the three-legged bedside table, her squat hand-painted pine dresser, a splotchy framed mirror, the spindled bathroom corner shelfall found curbside on garbage day.

Her perfect older sister, Pia, lives in an endless house in Connecticut with her handsome, thick-haired husband, Will, her tween daughter, Emma, and a frothy, russet-colored Labradoodle named Root Beer. Pia is altogether Muriels opposite. Muriel eats takeout from the carton; Pia makes salads from the microgreens in her garden. Pia takes me time to pray and do yoga. She believes every word in the bible, her faith pure and unquestioning. Pia is remarkably like their mother, Lidia. Or so Lidia would have Pia believe. Muriel knows better. Years earlier she discovered the truth about her mothers liesnot that shell ever tell.

The story begins on an ordinary Saturday which turns out to be anything but. When Pia calls Muriel out of the blue, Muriel expects the same lecture about slimming down, toning up, highlighting her hair, getting a better job, and moving into an elevator building. Only this time its different. Distressingly so. Pia takes the train into the city to visit her sister and leave her withyet anotherterrible secret she is sworn to keep.