Sentenced: The Atrocity Archives by Charles Stross
There are luminous worms writing behind his eyes.
The Atrocity Archives by Charles Stross
In the second chapter Bob Howard comes face to face with the horrors from beyond, in (or behind) the face of a co-worker from accounting being possessed. There is a whole setup that resonates with anyone who has done tech support or had to deal with the incompetence of others. Between this and a touch of dialog, Stross manages to convey a whole universe of terror, without using the word ‘eldritch’ once.