After much delay, I finally got a copy of Canis Mysterium (Chaosium 23124). Unlike other books that have been out longer, I was excited to get this as it's (a) a stand alone CoC supplement and (b) is only $10.95. I wasn't expecting a large tome for that price, and I wasn't disappointed.
Plot: It's 1930 and a team of researchers and students (Psychology) from Miskatonic are called to the town of Coldwater Falls to investigate a man who acts like a dog, a particularly violent one if the evidence proves correct.
Any CoC player of any experience is anticipating the big bad hiding around Coldwater Falls (hint: it's NOT a werewolf) and the cover of the scenario helps seal it. Outside a few possible deviations, your assumption holds true.
While I understand the plot device to drop this into the 1930s, this scenario feels in a better like a scenario for beginning players/investigators and that sort of avoids large swaths of Chaosium's product line without some possibly significant revisions. With that said, the 32 page scenario could greatly benefit from the removal of the ghastly artwork and the inclusion of six pregenerated investigators. If a keeper were to run this, the precluded notion that everyone is part of the Miskatonic U's Department of Biology to achieve the ultimate motivations should demand such an inclusion.
Despite my excitement for a relatively inexpensive, stand-alone published scenario, there are better and longer scenarios offered for free on the Chaosium and yog-sothoth.com websites. It's with much sadness, that I must rate this book just one gnome out of five.
There are so many better books and scenarios that deal with the big baddie that I can't justify this purchase other than a test run of the special ordering from my new FLGS.
In fairness, I may come to run this if I stumble upon a group of new people interested in learning RPGs and interested in mysteries. It's not The Haunting, but I could justify building all those pre-gens.