Amelia Cooper has moved to London and is a detective, but now working at a new location. She now works with Scotland Yard, but mainly alone. During a midnight stroll in London, she sees two men bickering back and forth at one another. She helps them solve a case by saying two words and they are off. Thinking she would never see them again, she leaves them with a shameless question, which makes them both stunned. Sherlock believes he keeps Amelia around because she is good at solving riddles and deducing, but their is something unusually different about her and he is going to discover it.

An old friend of Sherlock's somehow gets wrapped up in his and John's adventures...yes, a FRIEND. See what happens when everybody's favorite sociopath reacquaints with this old friend, and what will John and the others think about it?