Season 2, Episode 21:
Northwest Passage
After learning his true origins in "The Man from the Other Side," Peter leaves Boston and travels to a small town in the state of Washington. At a diner, Peter makes plans for a date with a waitress named Krista, but before they can meet she is kidnapped and murdered. Initially, the authorities suspect Peter is involved in the disappearance, until told he was at his motel all night. Peter decides to aid them in the investigation after catching a glimpse of Thomas Jerome Newton, believing the shapeshifters are responsible and are coming after him; however, he does not wish Walter to be involved, asking Broyles to keep his location secret.
During the autopsy, Peter explains to Sheriff Mathis how removing a part of a brain could provide information to the killers. Mathis' partner, Deputy Bill Ferguson, soon disappears as well. After they go to the scene of Krista's murder, Peter encounters Newton, but he escapes. Peter becomes suspicious of Mathis when he sees blood on her jacket; however, he believes her when she shows him her cut from a fall, which is bleeding normal blood, not the mercury typical of shapeshifters; he then explains the concept of shapeshifters to her.
Peter begins to doubt the shapeshifters' motives after another body is found, but eventually comes up with an idea to read and track the victims' adrenaline spikes, which allows him to find where the murders took place: a dairy farm. They find the owner, who confesses to killing the women because they rejected him, and kidnapped and tortured Mathis's partner when he discovered the culprit. Repeatedly at the motel, Peter receives calls with static, strange noises, and clicks, which he suspects are coming from Newton. In the end, Peter prepares to head back to Boston, but is approached by Newton, who has brought "Mr. Secretary", the man from crossed over at the bridge, to see Peter. The man is revealed to be his actual father from the alternate universe, "Walternate".
Meanwhile, back in Boston, a distraught Walter suffers a small mental breakdown at a supermarket. Olivia and Astrid escort him home, discovering his house is in disarray. After they ask why he didn't come to them for help, Walter replies he needs to learn to care for himself if Peter fails to return. He discovers a way to find Peter using his unique energy signature, but changes his mind after worrying that Peter will not forgive him. However, Olivia learns Peter's whereabouts from Broyles; they prepare to fly to Washington.
