Chasing Echos: A Sherlock Fanfic

Sherlock Holmes and John Watson are carrying on with their usual routines; investigating and crime-fighting. Their lives are as "normal" as they could be, Sherlock being a highly functioning sociopath and all, when someone neither John or Sherlock were expecting showed up at their door. This feisty, unbelievably smart, blood-covered red head took Baker Street by storm, revealing her twisted past, and becoming unbelievably fond of the boys, and vice versa. But what will happen if her past comes back to haunt her? Who is after her?