"The Adventure of the Chinese Dog" is the sole episode of the Ellery Queen TV series set in the small, fictional town in Wrightsville. This ties it into the books, albeit in a rather paradoxical way.
Some background. Wrightsville was a New England town first appearing in 1942's Calamity Town. Initially it was a place for Ellery to get away and finish a novel without any other duties or distractions. (Calamity Town follows through to the point where he's initially referred to only by the pseudonym he's staying under. He only becomes "Ellery Queen" when one of the characters finds him out through detective work of her own.) But he becomes involved in a murder case. He goes back in later novels and it happens again. And these murders catch him off balance. In New York and Hollywood he accepts homicide as an unpleasant part of life, one that can keep him occupied. The quieter reaches of America are supposed to be freer of vice. But beneath the surface violence rages on, resulting in tragedies even he can't prevent. Et in Arcadia ego.
In the Wrightsville novels the Queen series begins to become more character-based, and sometimes darker. Ten Days' Wonder was so traumatic for the lead character that he gave up sleuthing until a (New York City-based) serial killer necessitated his comeback in Cat of Many Tails. It's quite plausible that the change in tone was the result of defensive anxiety. When the US got involved with World War Two, many mystery authors shelved their series characters while changing their output to hard-hitting war and political stories. Dannay and Lee kept their cash cow series going, but they could at least show that their whodunits had something to say. In any case, the results were quite good, and the cousins were able to use the new tricks they'd picked up in postwar novels as well, set in Wrightsville and elsewhere.
In tone "The Adventure of the Chinese Dog" somewhat upends all this worthy angst. There's a murder, of course, but it's still a light entry in a series that by and large keeps a light tone. (There are a couple of exceptions.) The overall impression is that the locals think they - and more importantly, each other - have secrets worth killing over, most are misinformed on this point.
One difference is that Ellery isn't as lost at sea here, not as isolated. While the books had him going to Wrightsville to get away from it all, with the result that once jealousy and murder come to the fore he's without the counsel of dear old papa and the friendly police detectives, the trip here is a family one. Specifically Inspector Richard Queen drags Ellery off on a fishing trip, himself having a kind of Captain Ahab thing with a large local trout. So while dad is initially disinterested in the murder, preoccupied as he is with proving his anglerhood, he's there to help in his cantankerous way. Even Velie gets to show up for a couple of brief scenes, when some work needs to be done back in the Big Apple.
The murder? Eben Wright, the president of a boot manufacturer and descendant of the town founder, is struck over the head with the title dog, an ancient Chinese statue encrusted with precious jewels. The dog is intended as a wedding present to his daughter. Not one that she wanted, though. She'd prefer a partnership in the family business for her hilariously meatheaded fiance. Also disgruntled are a twitchy nephew who's also being kept out of the upper echelons of the company and a housekeeper whose longstanding amour with her employer seems to have meant less to him than to her. This last is played by Geraldine Brooks in the show's best guest performance to date, one that will be hard to top. It's all the more heartbreaking that the actress would die within a couple of years, like Jim Hutton himself and a number of other guest stars.
But back to the matter at hand. The given motives of most of the suspects don't quite hold water. And in fact the real motive of the real killer turns out to be quite a bit more basic. Ellery winds up figuring it out during one of his funnier break-the-fourth-wall eureka moments. When the solution is finally revealed it makes sense in all the important ways, even if it bears little relation to real-life detective work.
A note on the location of Wrightsville. In the books it's never specified beyond New England. My impression always tracked with the Northeast Kingdom - especially New Hampshire - given its isolation. In this episode it's drivable from New York in a forties car, so it seems more like Connecticut - which would technically still be New England - or Upstate New York - which wouldn't. Still, whenever the characters are outside it looks a hell of a lot like the rural parts of Southern California.