Tonight’s all new Elementary season 3, episode 19, “One Watson, One Holmes,” stumbles into a viral civil war.

Everyone is a reliable collective of individuals whose hacking skills are uncontested. They have the ability to ruin your life in a matter of seconds and access backlogs of data from nearly any source. So what happens when they turn on each other? Tonight’s Elementary endeavours to find out.

Previously on ‘Elementary’

The ride share company Zooss was doing more than taking their clients from Point A to Point B. Once the engineers got a taste for the view from high above, they could not help but exploit their positions for blackmailing and stalking some regular customers. While Joan worked on putting the murder in context, Sherlock’s attention was elsewhere as he worked out why one of his irregulars was seeking to have a child a with him. Turns out Holmes Sr. is in need of a heir to ensure the family name lives beyond Sherlock.

Related: Elementary season 3, episode 18 recap: Fall of the mighty”

This week on ‘Elementary’

Something bigger than a comment war is breaking out on the Internet on this week’s Elementary. When a member of the hacker collective Everyone turns up dead, Sherlock and Joan dive into the middle of a war breaking out amongst the members of the group.

This is not the first time, nor will it be the last, that Joan and Sherlock have worked with Everyone. For a more in depth look at their history with the hackers check out Elementary season 3, episode 19 unmasks Everyone.

Watch the promo for tonight’s episode here.

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