Mulder spirals down into the mind of a serial killer, losing himself in the process.
Injured in the search for Priest, Mulder has no identity. Lost in the mind of the killer, and in the bowels of New York, he is drawn to dark deeds through the twisted lies he is being fed.
Mulder's profiling ability reveals the terrible toll it takes on him as the search for Priest continues.
Mulder is in torment as he continues to drop into Priest's mind. The search accelerates as the stakes are raised.
With Priest defeated, Mulder and Scully move forward.