The classic setup for a mystery is a murder, but it can also be fun to do a bit of lower-stakes problem-solving, too. In this case, the beer in the local pub has all gone bad, and it falls to you to figure out why. Speaking personally, I wouldn't be able to tell the difference between a good beer and "something really bad, rotten, just all wrong", but to the protagonist this is very important.
Searching through the pub, you find some clues, and the supernatural elements build in a very effective way; I loved the vignettes with the fridge and the cellar, for example. And then you're suddenly experiencing the moment of the ghost's death, and have to prevent it. The prose is very effective and conveys the mood without going purple, and the little moments of "wait, what's happening" were a definite high point. I also liked how the search for clues was implemented thoroughly but dully, to contrast the mundane investigation you've been tasked with against the unexplainable interruptions.
Beyond that, though, it didn't quite manage to stick the landing, for me. Preventing a ghost's death in the past is a great hook for a puzzle, but the puzzle itself ((Spoiler - click to show)pick up object, take it to room) felt underwhelming by comparison, and some aspects (like looping through the scene exactly three times, no more) felt more like contrivances than mysteries. There's also a bit of an over-reliance on "You can see X here" when I think custom-written paragraphs would have provided more flavor.
The game also presents an ASK/TELL conversation system with a TOPICS command, but TOPICS always tells you the same thing (rather than adapting to what's happened), and most things I tried to ASK/TELL about got default responses, which left me playing guess-the-noun (and finding the whole process a bit unsatisfying). I think a TALK TO command might have worked better here, or a choice-based conversation system; as it stands, I got somewhat bogged down in a comparatively uninteresting part of the game.
Overall, I enjoyed it, and the bait-and-switch in the first part is very well orchestrated. I just would have liked the standard Inform mechanics to get out of my way a little more and stop clouding the well-written prose.