The hacker group “Everyone” becomes both the suspect and the victim in this week’s Elementary. How much do we know about the mysterious group?

Elementary season 3, episode 19, “One Watson, One Holmes,” will unmask at least two members of the hacker group “Everyone.” Over the course of three seasons, Everyone has gotten Sherlock to perform humiliating tasks in exchange for information. From singing the soundtrack to Frozen in a giant prom dress, to standing outdoors getting punched in the arm, Sherlock’s penance for information has a wide range.

But this week’s episode pulls back the curtain when a member of Everyone, and common acquaintance of Sherlock, is murdered. Watch the clip here.

In the past, Everyone has made quite the mess of things for Sherlock and Joan. In the season 2 episode, “We Are Everyone,” the group hopes to obtain a safe haven for a man who leaked classified documents on the Internet. Sherlock and Joan throw themselves at the mercy of Everyone. When it is made known that they are looking for the man, the network bands together to hack every online profile, cell phone, landline, and television the detectives have access to. SHolmes221B is officially initiated with a shoe on his head by the end of the episode.

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Although the group is primarily used for information, they have also been summoned for protection. When Joan felt she would be threatened by a prominent member of British Intelligence in “The Grand Experiment,” she pulls up a call with quite a few members of Everyone as witnesses to their interaction.

Everyone has become a staple in the Elementary world that Sherlock and Joan have built. They are an invaluable resource for finding old social networking caches, tracking purchases, and providing excellent mental images of Sherlock performing some incredible tasks.

Watch Elementary season 3, episode 19, “One Watson, One Holmes,” Thursday, April 9 at 10:00 p.m. ET on CBS.