A fistful of collars : a Chet and Bernie mystery / Spencer Quinn.

Enhanced descriptions from Syndetics:

Chet the dog and Bernie, his private investigator companion, are back in the New York Times bestselling mystery series as they investigate a movie star with a shady past.

Everyone's favorite detective team returns in a new adventure as canine narrator Chet and his human partner P.I. Bernie Little find that Hollywood has gone to the dogs.

Hoping to bring some Tinseltown money to the Valley, the mayor lures a movie studio to town to shoot their next production, a big-budget Western in the classic tradition. The star is none other than ruggedly handsome--and notoriously badly behaved--Thad Perry. When the mayor decides that someone needs to keep an eye on Thad so that he doesn't get into too much trouble, Bernie and Chet are handpicked for the job. The money is good but something smells fishy, and what should have been a simple matter of babysitting soon gets more complicated--especially when they discover that Thad has a mysterious connection to the Valley that nobody wants to talk about. What kind of secret could Thad have left behind when he went to Hollywood to seek fame and fortune? The only people who might know the answer have a bad habit of turning up dead before they can talk.

As Bernie's relationship with his longtime girlfriend Suzie goes long-distance, and Chet's late-night assignations appear to have resulted in an unexpected dividend, it's all our two sleuths can do to keep Thad and his motley entourage of yes-men, handlers, and hangers-on in their sights. Worst of all, Thad is a self-proclaimed cat person, and his feline friend Brando has taken an instant dislike to Chet.

Like the winning books before it, this fifth book in the series combines a top-notch mystery with genuine humor and a perceptive take on the relationship between human and dog that will stay with you long after the case is solved.