Fifteen years ago, a teenage girl fell into a canal late at night. Unable to swim, she went under and started to drown, only surviving thanks to a nearby man, an alcoholic, who heard her splashes and pulled her out, though not before she suffered irreparable brain damage that left her in a state of permanent childhood, unable to learn or mature. The drunk man claimed he saw her thrown into the canal by another man, but the following day he couldn't remember a thing. Now, at a fundraising dinner for a Venetian charity, a wealthy and aristocratic patroness -- the girl's grandmother -- asks Brunetti if he will investigate. Brunetti's not sure what to do. If a crime was committed, it would surely have passed the statute of limitations. But out of a mixture of curiosity, pity, and a willingness to fulfill the wishes of a guilt-wracked older woman, who happens to be his mother-in-law's best friend, he agrees. Awash in the rhythms and concerns of contemporary Venetian life, from historical preservation, to housing, to new waves of African migrants, and the haunting story of a woman trapped in a damaged perpetual childhood, Brunetti soon finds himself unable to let the case rest, if indeed there is a case.