Amanda Eyre Ward's prose is clear-headed and crisp as if laid down by a proper, uniformed maid and it well serves a plot that could have gotten soggy. Caroline Winters, a piano prodigy-turned-New Orleans barmaid, launches a search for her sister Ellie, who vanished 15 years ago. Ward's ambitious but uneven novel flits from Caroline's childhood to her mother's own mournful story, interweaving letters from a mysterious woman only identified at the end. Early scenes in New Orleans are plump with details, but the final third feels like a mere series of sketches. Spare is nice, but How to be Lost feels almost scanty.