Harry Potter and the Strange Visitors

John's sister, Harry, has gone missing. Sherlock decides to look into the case and finds it leads to the Daleks - and his brother, the Doctor, who brings along his companion, Clara. Along with the Golden Trio, whom they pick up along the way, they set out to save their planet - along with their friends and family.

[may contain some mature themes - I will warn for them in the chapter heading when they apply, so please look for them]