Earthly Remains by Donna Leon

Brunetti is on a short sabbatical from the suffocating venality and other criminal behavior that he witnesses every day on the job. He retreats to an island in the Venetian lagoon north of the city, and finds instant peace and comfort in the rural isolation, physical exercise (cycling and rowing) and bonding with an old family friend, Davide Casati, who turns out to be the caretaker of the villa where Brunetti is in residence for two weeks.

A big, and fully enjoyable chunk of this novel, is focused on Brunetti's relationship with Casati and their time spent on the waters of the lagoon, observing wild life and the geographic marvels of the place. When Casati goes missing one morning, the story takes a turn toward the dark, and the rest of the novel is an investigation of the disappearance and Casati's past.

An enjoyable read.  I loved the descriptions of the rural area and all the canals outside the city.