After crossing paths with a vengeful group of survivors, Ellie's fighting spirit draws unwanted attention from its leader; still battling for his life, a weakened Joel faces off with a hunting party out for blood.
Joan and Kitty try to prove that a string of murders is connected to an international government conspiracy involving the Defense Intelligence Agency; Sherlock and Kitty's relationship is strained after she shares lifechanging news.
Holmes' former protégé, Kitty Winter, warns him of a killer who is eliminating everyone involved with a case they worked on together in London; Watson discovers that Kitty has a lifechanging secret.