When they come to pick up their order, the shopkeeper fairy waves to them and gestures to the package sitting next to them on the counter.

"Thank you for your order! Come back when you have more crystals!"

Inside the package, McGillis will find:
❦ Letters: The letters are addressed to Sherlock Holmes, confessing his feelings for Sherlock and also the location of their final confrontation and where Sherlock could find the evidence to pin him as the Lord of Crimes.