On Sunday’s Season 4 finale of Sherlock, Sherlock found out more about his forgotten sister, Eurus. After discovering she was locked away in a prison fortress on a remote island, Sherlock, Mycroft, and Watson broke into the facility to find out how she’d previously escaped. She was held in a room that resembled Hannibal Lecter’s dungeon cell.
Soon Sherlock, Watson, and Mycroft learned that due to her superior intellect and a brief meeting with Moriarty five years ago, Eurus had complete control over the prison.
She began playing mind games with the group. Eurus forced Sherlock to have Molly Hooper tell him she loved him. Then the Holmes brothers were turned on themselves as Sherlock had to choose between killing Watson or Mycroft. Mycroft urged Sherlock to sacrifice him, but “not [shoot him] in the face, though, please. I promised my brain to the Royal Society.”
Thankfully, the Brothers Holmes escaped the predicament and put Eurus back in her cell. The season ended with a montage that flashed forward to show the entire Holmes family visiting Eurus, as Sherlock and Watson watched a message on a DVD from Mary, who said her boys would always be at Baker Street.
Watch: ‘Sherlock’ creator fires back at critic in rhyme: