The premise of the adventure is simple: an alchemist with more money than sense has disappeared and his adoring wife is prepared to part with a goodly chunk of his wealth to get him back. What adventurer worth the name could possibly refuse?
The DM's introduction explains succinctly what the problem really is, and then settles down to set the scene in detail. The missing alchemist lived in a country castle (I did say he was well-off...) with a nearby village: there's loads of information to enable you to run the castle and village well, but without constraining you as to just where or in what country it is, so it can be located wherever convenient within your campaign world. There is quite a bit of information to pick up in the village, should the characters be prepared to go and ask... and then on to the castle itself, easily found about four miles away within thick forest.
The castle rooms are clearly described and, given the underlying rationale for what's actually happened to the alchemist, logical - although until the characters deduce just what has taken place, quite baffling. There are opportunities for those characters who like to work things out and for whom combat is not the only way of interacting with everyone you meet in the 'dungeon' part of an adventure, but plenty of scope to exercise the sword arm and practise offensive spellcasting as well: a nice balance. Provided that the characters make their way through the castle, they can find out where and how to set things aright... and of course there's a good final conflict scene in which they have the opportunity to do just that.
This is a neat little adventure, which should occupy an evening's play - perhaps an interlude when characters are travelling, or an opportunity to top up their funds with a bit of honest adventuring if finaces are low. Unless a wizard gets fascinated by the alchemist's work, there is not much, however, to build on: complete the adventure and move on. Hence it could serve as a 'one-off' game if required.