I have decided to convert an excellent old Call of Cthulhu adventure pack titled Horror on the Orient Express for the Grimm RPG.
Instead of the Orient Express, I will set it in the Polar Express (as in the animated Tom Hanks movie) where the children travel towards the North Pole during Christmas Eve only to be diverted into the Grimm Lands by some sinister plot!
I'm yet to work out some of the details, but I'm convinced it'll be a fun adventure to run.