There are many forgotten games we played as children, one of which was tag. You would call "Tag, you're it!" just before making physical contact with another and something would pass from you to them, but what if that thing left something behind in you too?
An unknown entity has infiltrated an office, whilst the staff go about their daily routines unaware of its presence. As it systematically picks its victims, will those who remain suspect anything or will it succeed in consuming them all?