Oh! I forgot! I have 2 adventures for ars màgica saber on my blog that might be useful. They are not mine, but I have them there for reference since I found they were great for a single session play. One is about dealing with a giant and his heart's love. The other is about a curse that you can break with some thinking. Both are better with grogs than with mages.
They say it takes one hour to play, buy they tend to me o e session. One hour is extremely optimistic.
There is a third adventure in the blog (blood on his hands) but it is less suitable for grogs onlyn since it does not pass the 3 clue rule from the previous posts.
I have played all 3 adventure at least once and they work well. Going home is none of my "going to" easy prep adventure when I have to improvise something, since it works the same regardless of the rules system you ar le using. It can be complemented with an early or late combat against ruffians if your party wants some action. It could also be tied to your investigation for the list companion: have the companion wake up with the ring in his possession.