After a Government Minister dies in curious circumstances, Mycroft sends Greg and Sherlock to investigate. When an infectious disease is discovered, Mycroft is forced to quarantine the village, knowing it may mean the deaths of both his brother and his lover.
When Greg Lestrade met Mycroft Holmes for the first time he wasn't quite sure what to make of him. But nine years down the line, he could never have dreamed that this was where they were going to end up. AKA: A slow-burn Mystrade, starting in 2005 and covering all three seasons of Sherlock.
After getting trapped in Mycroft's office following a bomb, he and Greg finally get around to negotiating their relationship.