I haven't heard anyone mention the evil twin theory yet?!? The line from the synopsis< "unstoppable force of terror from within
their own organization" immediately reminded me of the enemy within. And that shot of kirk and Cumberbatch staring at each other thru the glass was kind of eery. And evil twins, come on, there were evil twins in every other episode. And one last thing, in one shot Cumberbatch is wearing a jacket with little ribs on the shoulder somewhat reminiscent of Lore's jacket.
Just another theory.