Douglas wears bright blue-glass spectacles. The reason for this is known only to him and to a man knifed open and killed twenty, thirty years ago. Seven murders later, one of Douglas's intended victims sees him coming. And it turns out that he's not going to permit his own death. Sherlock crossover with Ray Bradbury's macabre short story "The Man Upstairs".

ASOUE-BBC Sherlock cross. And how, exactly, does a detective with a smartphone live at the same time as three orphans who send telegraphs? I don't know, but I hope you'll enjoy this anyway. Set after The Reichenbach Fall, and should be spoiler-free for The Empty Hearse. (Work-in-progress! Feedback appreciated!)

Sherlock and John are summoned to find a missing ballet teacher, and Sherlock recalls the meeting of two extraordinary minds. Crossover with Noel Streatfeild's "Ballet Shoes."

Arsene Lupin/Ellery Queen: When Ellery went to France, he discovered just how differently the French do things, how insane Arsène is, and how determined Ganimard is at his job. Then he went to London and things got really weird.

Long-distance relationships can be both surprisingly tough and surprisingly easy. And sometimes they're surprisingly ridiculous. Or, Arsène pisses people off and Ellery takes the fall, repeatedly and across oceans. Arsene Lupin/Ellery Queen hints.