Fringe: Reciprocity

"Reciprocity" is the eleventh episode of the third season of the American science fiction drama television series Fringe, and the 54th episode overall. In the episode, the Fringe division follows a chain of shapeshifter murders as the assembly of the doomsday device nears completion. Ryan McDonald and Charles Parnell guest starred. Co-executive producer Josh Singer wrote "Reciprocity", his seventh such credit for the series. For his third Fringe directional credit, Jeannot Szwarc served as the director. The episode first aired in the United States on January 28, 2011 to an estimated 4.57 million viewers, making it the highest rated program of the night. Television critics generally viewed the episode positively, with a number praising the reveal of the shapeshifter killer's identity.