young sherlock holmes or young sherlock holmes and the pyramid of fear (1985) is basically a boarding school au but the film also leaves the possibility to simply be a prequel to the canon we know.
as the titles suggest, this film features young sherlock holmes and young john watson meeting and solving a mystery together. along for the ride is also elizabeth, a close friend of sherlock.
the case involves two murders that lead the trio to a mysterious cult and they soon realise there might be more at stake than they first thought.
this movie has both the cute, funny school adventure as well as genuinely scary and tragic scenes. it explains some things about the man sherlock holmes will become later on and in my opinion it’s really entertaining!
important: don’t skip the end of the movie. there is an after-credits scene and it matters. trust me.
you can watch it here