Mr. DuLac’s review published on Letterboxd:
One of our guests is a werewolf, I know it.
A lightweight horror romp by Amicus Studios, which I've always seen as the lower budget version of Hammer Films. It has a nice little setup of a murder mystery hybrid where instead of knowing there's a murderer amongst a group, they know there's a werewolf!
Unfortunately the producer Milton Subotsky decided to tack on the added gimmick of having a narrator explain to the audience at the beginning that this was a "Werewolf Mystery" and to place close attention to the clues so you could guess who the werewolf was during the "Werewolf Break". The break is actually a 30 second interruption during the climax of the film where everything stops so you can guess who the werewolf is.
Needless to say the film would have worked better without that gimmick, but is still a bit of fun with the unusual casting of Calvin Lockhart in the lead of a horror film, despite the poster clearly suggesting that Peter Cushing is. Even in a supporting role he always elevated a horror film though, even one that has a German Shepard as it's werewolf stand-in.