"The Number of the Beast is 666" is the twelfth episode of Season 3. It aired on August 22, 2015.
Plot
Will Graham and the FBI enlist the expertise of Dr. Frederick Chilton in the hopes of luring Francis Dolarhyde into an ambush, using Freddie Lounds as their mouthpiece. As Will's empathy for Dolarhyde begins to affect his fragile psyche, Bedelia Du Maurier warns that the killer Will should be most concerned about at the moment is himself. Meanwhile, Dolarhyde senses that the FBI is closing in and launches a horrifying endgame.