Murder at the Diogenes Club

When Sherlock receives a text from Lestrade regarding a murder of a man in a suit at the Diogenes Club, his blood freezes and his heart constricts in an extremely painful way that could only translate to shock, concern and most frightening of all, sentiment.

Mycroft is certain that no one would miss him if he were to die. He is surprised to find that he is completely and utterly incorrect in his conclusion.