Plot summary
Two years after his reported Reichenbach Fall demise, Sherlock, who has been cleared of all fraud charges against him, returns with Mycroft's help to a London under threat of terrorist attack. He tries to convince John—who has moved on and now has a girlfriend, Mary Morstan ( Amanda Abbington )—to help; however, John is angry that Sherlock did not tell him he was alive. Instead, Sherlock enlists Molly to assist him, but when John is kidnapped by unknown assailants and is rescued by Sherlock and Mary, he returns to help find the terrorists and foil an underground plot to blow up the Houses of Parliament during an all-night sitting on Guy Fawkes Night. Based on the short story " The Adventure of the Empty House ", and " The Lost Special " with numerous references to other works by Sir Arthur Conan Doyle, and other adaptations of the original stories.
Credits
Adapted from Wikipedia contributors, List of Sherlock episodes. HTML formatting and reference markers removed.