Here's the official guide of Elementary episode 21 "A Landmark Story". This episode airs on Thursday, May 2 on ABC.
SHERLOCK CONTINUES HIS HUNT FOR MORIARTY WHEN SEBASTIAN MORAN, A.K.A “M,” RETURNS AND REVEALS THAT SHERLOCK’S NEMESIS MAY BE RESPONSIBLE FOR A SERIES OF RECENT MURDERS --
Vinnie Jones Returns as the Sinister Sebastian Moran, a.k.a. “M.”
F. Murray Abraham Guest Stars as “The Actuary,” a Devious Hitman
WCBS News Anchor Kristine Johnson Makes a Cameo as a News Reporter
- Sherlock resumes his hunt for Moriarty when Sebastian Moran reveals that a man who was thought to be dead from a heart attack was actually on the list of intended victims from Moriarty.