In the season two premiere we are taken to London where Sherlock goes to prove one of his former colleagues theory right. While in London Sherlock encounters his long lost brother Mycroft, whose relationship is strained due to the fact that Sherlock slept with Mycroft's fiance. Joan suggests that Sherlock try to embrace "Step Nine" of his recovery and make amends with people from his past. Sherlock investigates a theory that the killer used a "Plastic Gun" and was able to dispose of it to cover up the murder. As always, he was right. Joan and Sherlock discuss Joan's sex life and how they could never sleep together because they're colleagues. When Joan and Mycroft go to dinner it is discovered he recently beat cancer and is looking to making amends with Sherlock. In the end, Mycroft blows up all of Sherlock's belongings. From this act Sherlock and Mycroft make amends.