This post contains spoilers for Alan Wake.
Events in The Signal take place right after the end of Alan Wake. Wake finds himself in a nightmarish world, a place “familiar, but wrong, somehow,” and an image of Thomas Zane in a bathroom mirror explains that Wake himself is “the one making all this happen.” That’s an interesting line because it implies that Wake is creating the world around him, not the Dark Presence. Throughout the DLC we see Wake on television screens, lying on the floor of the cabin’s attic where his typewriter is, rambling what seems like nonsense. Zane explains that this is the real Alan Wake, a claim that’s proven when the ramblings come true.