The Sound and the Furry by Spencer Quinn

When Chet and Bernie happen upon a prison work crew that includes Frenchie Boutette, an old criminal pal they sent up the river, getting a new case is the last thing they expect. But Frenchie, who comes from an old Louisiana family full of black sheep, needs help finding his one law-abiding relative, his brother Ralph, a reclusive inventor who has gone missing with his houseboat. Though he's temped to take another job (with a big payday) in Alaska, Bernie decides to set course for the bayous of Louisiana, a trip that will introduce Chet to a world of sights, smells, and tastes that are like nothing he's ever encountered.

Out in bayou country, Chet and Bernie meet the no-good Boutette family and their ancient enemies, the maybe-even-worse Robideaus, and at first it seems as if Ralph's disappearance is connected to a dispute over a load of stolen shrimp. but when Chet uncovers a buried clue, the investigation heads in a dangerous new direction involving the oil business and an impending environmental catastrophe. The more Chet and Bernie discover about Ralph, the more treacherous the job becomes, and soon they're fighting not only Big Oil, but also shadowy black ops figures, a violent biker gang from back home, and Iko - a legendary bayou gator with a seemingly insatiable appetite. Meanwhile, deep under the Gulf, the pressure just keeps building.

With top-notch suspense, humor, and genuine insight into the ways our canine companions think and behave - all set against a rollicking new Louisiana backdrop - The Sound and the Furry will make you howl in delight. 

There really isn't much I can say, except it's another great entry in one of my favorite series. I liked that Chet got to describe lots of different smells, especially the ones relating to water. Living in the desert, most of the books don't go into wet smells, just Bernie's rants about the aquifer and such.

I was surprised by one of the relationships, and thought it was very cool of the author to include it. And I love, love, love Chet's way of explaining how alligators smell!