Sherlock Season 4: 18 Easter Eggs & References From 'The Lying Detective'

After the season four premiere received a mixed reception, Sherlock grabbed its audience by the throat in its shocking, emotional rollercoaster of a middle episode. Titled The Lying Detective, we had Sherlock going off the deep end, John broken with grief, a creepy villain and a massive show-stopping reveal. Last chance, people, if you haven't caught up with the latest episode yet, you're about to get spoiled.

In the episode's closing moments, we find out that John's bus lady mistress, fake-out Faith Smith and the German therapist are all the same woman - Sherlock and Mycroft's secret sister, Eurus. It's an exciting deviation from the traditional Sherlock Holmes story which will hopefully lead to an explosive season (possibly series) finale next week.

In other areas, however, this episode paid a lot of tribute to the work of Arthur Conan Doyle. Read on for 18 easter eggs, references and connections that you might well have missed in The Lying Detective.

The Lying Detective is a loose adaptation of Doyle's The Adventure of the Dying Detective. Like many previous Sherlock episodes, the original story forms the broad basis of the story with lots of elements expanded and altered.

The inciting incident of both is when Mrs Hudson visits Dr Watson and pleads with him to see Sherlock, as she believes the detective is on his last legs. In Doyle's tale, though, Hudders does not drive to John in an Aston Martin with Sherlock bundled in the boot.

The central idea of Sherlock pretending to be moments from death as a way to get Smith to confess to his crimes is also lifted from Doyle. In the original, Watson is hiding in the room and overhears the confession. In Sherlock, it is John's walking stick which provides Smith's downfall.

A nice little detail lifted from the story is that Sherlock's walls are covered with pictures of Culverton Smith, much like the images of "celebrated criminals" that adorn Baker Street in the short story.