This is sheer brilliance. I never would have thought a Great Mouse Detective/Sherlock crossover could work...until I read your story! I LOVE the way you've managed to keep those elements from The Great Mouse Detective that work so well and yet update this world to work within the Sherlock universe. I got such a kick out of things like the Holeless Network and St Gertrude's Mouse Hospital. And I have to commend you on the excellent description of Basil's investigation and his deductions. Lastly, I was delighted by the appearance of Toby (and those attempts to deliver that letter to John) not to mention the "I Believe in Sherlock" that Basil pastes to their wall.

I'm so bookmarking this in my Pinboard (https://pinboard.in/u:rusty_armour) account. :-D