In the BBC series Sherlock, what is the title of the episode introducing Mary Morstan?

The Sherlock episode introducing Mary Morstan is “The Empty Hearse.”

Mary Morstan, played by Amanda Abbington, is introduced as John Watson’s partner when Sherlock returns after his apparent death. The episode is the opening story of series 3 and premiered on BBC One on 1 January 2014.

In Arthur Conan Doyle’s original stories, Mary Morstan first appears in The Sign of the Four. Sherlock adapts that character into a modern professional woman whose relationship with John becomes central to the later series.

A frequent mix-up is “The Sign of Three,” which is the next episode and focuses on John and Mary’s wedding. “The Six Thatchers” is Mary’s major series 4 episode, but it does not introduce her.