Holmes and Watson investigate the murder of a former professional eSports video game player who died after being assaulted in front of his fans during a live video stream. Also, Shinwell approaches Joan for advice when his teenage daughter asks to meet with him for the first time in years.

Joan and Kitty try to prove that a string of murders, stemming from an old case Sherlock and Kitty solved in London, is connected to an international government conspiracy with the Defense Intelligence Agency at its center. Also, Sherlock and Kitty's relationship is strained after she shares life-changing news.