|“|| Stiles: "We're back to Telluric Currents?"|
Scott: "If the Dread Doctors didn't like coming into Eichen House because of them, maybe we can use them to protect Hayden."
Stiles: "Okay, so, besides Eichen, where's the strongest convergence?"
Scott: "We're standing on it."
Stiles: "[...] But it's just a school, though. You know, it's not exactly a fortress."
Scott: "Lydia's got an idea for that. Remember how Valack quoted Tesla? [...] She thinks maybe it was a clue."
Stiles: "To do what?"
Scott: "To disrupt their frequency."
Theo convinces Stiles to help him conceal the truth about Josh's death at Theo's hands by using the fact that Theo knows Stiles killed Donovan and kept it secret from the rest of the McCall Pack. Hayden becomes irritated by Liam's attempt to reveal the existence of the supernatural world to her and his belief that she is a Chimera. Liam tries to convince her by triggering his glowing gold eyes, claws, and fangs and roaring in her face, but all this does is scare her to the point that she punched him in the face, giving him a bloody nose before she drives away.
Hayden stops on a road near the Beacon Hills Preserve to check on her hand, which went from having bloody and slightly dislocated knuckles to being completely healed right before her eyes. Just then, she's confronted by the Dread Doctors, who use their electromagnetokinetic powers to lock her car doors and prevent her engine from starting so she can't escape. When they start chanting her name through the car radio, Liam arrives and saves her by pulling her out through the broken moon roof and helping her run away. He then takes her to the McCall House to seek Scott's help in figuring out their current situation. However, right as Scott and Stiles returned to the house, they find Hayden in Scott's bathroom after having uncontrollably shifting with glowing gold eyes, claws, and fangs, revealing that she is part-Werewolf. Mason befriends Corey, Lucas's ex-boyfriend, and discovers that Corey, too, is a Chimera after learning that Corey rapidly healed from the wounds he received from Lucas' stingers.
The next day, Kira's mother, Noshiko, having noticed Kira's strange behavior recently, tests her Kitsune spirit by engaging her in a sparring match with their katanas. Kira loses control and slices her mother's sword in half before she was stopped by Ken using Kira's obsidian shuriken Kitsune tail, after which point Kira becomes upset and blames her mother for starting the sparring match, arguing that she could have killed her. Noshiko retorts that it wasn't Kira who almost killed her-- it was the Fox inside her. Later, Noshiko performs acupuncture on Kira's back at the Yukimura House and informs her that her human spirit and Fox spirit are out of balance, which is why the latter is fighting the former for control over her body.
Melissa McCall and Noah Stilinski research the known Chimeras' histories in an effort to find out what they have in common and discover that the Chimeras had all previously received organ or tissue transplants, making them humans with genetic chimerism even prior to becoming pseudo-supernatural Chimeras. Stiles and Theo agree to stake out the Beacon Hills Animal Clinic together, where they are keeping Josh's body, in hopes of finding out who has been stealing the bodies of the dead Chimeras. Meanwhile, Scott, Lydia, Malia, Parrish, and Liam set up a fortress to protect Hayden at Beacon Hills High School, using modified cellular frequency blockers in an effort to amplify the convergence of Telluric Currents through the earth at the high school, weaken the Dread Doctors, and prevent them from trying to capture Hayden again; however, unbeknownst to the others, Scott and Lydia secretly planned to try to capture one of the Doctors if the opportunity presented itself.
Ken and Noshiko go into Kira's bedroom to find that Kira has disappeared and has left the acupuncture pins in the headboard of her bed spelling "115" as a clue to where she went. After the Dread Doctors use their powers to induce terrifying hallucinations in Parrish, Malia, Scott, and Lydia, Parrish slips into a trance, shifts into Hellhound mode, and knocks out Theo and Stiles so he can steal Josh's body without revealing himself as the thief. The Doctors take advantage of the fact that Scott, Malia and Lydia are incapacitated by their hallucinations and capture both Hayden and Liam, bringing them back to their operating theater, where they hook Liam's arm up to a large IV drip of Wolfsbane and begin operating on Hayden right in front of him. Melissa returns to the McCall House to find a unknown female Chimera with long, pin-like claws is laying dead on her kitchen's table with Kira's katana-belt impaling her in the chest and screams in terror.
- Tyler Posey as Scott McCall
- Dylan O'Brien as Stiles Stilinski
- Holland Roden as Lydia Martin
- Shelley Hennig as Malia Tate
- Arden Cho as Kira Yukimura
- Dylan Sprayberry as Liam Dunbar
- Melissa Ponzio as Melissa McCall
- Linden Ashby as Sheriff Stilinski
- Ryan Kelley as Deputy Jordan Parrish
- Tamlyn Tomita as Noshiko Yukimura
- Cody Christian as Theo Raeken
- Khylin Rhambo as Mason Hewitt
- Kelsey Chow as Tracy Stewart
- Victoria Moroles as Hayden Romero
- Tom T. Choi as Ken Yukimura
- Benita Robledo as Deputy Valerie Clarke
- Michael Johnston as Corey
- Henry Zaga as Josh Diaz
- Marti Matulis as The Surgeon
- Douglas Tait as The Pathologist
- Caitlin Dechelle as The Geneticist
- Makenna James as Tara Raeken
- The title refers to the Dread Doctors, whose powers come from frequencies and vibrations, specifically electromagnetic ones.
- In this episode, the Dread Doctors used some sort of sound device to induce horrifying hallucinations in Scott, Lydia, Malia, and Parrish that would incapacitate them so they could capture Liam and Hayden. Each of them had hallucinations that involved their greatest fears at the time in some way.
- Scott hallucinated that Kira stabbed him in the chest with her katana, choked him with his now-deceased dog Roxie's leash, and told him she was the Messenger of Death, as Scott was afraid that her Kitsune spirit would make her like the Nogitsune.
- Parrish hallucinated that he passionately made out with Lydia before severely burning her with his Hellhound fire, as his biggest fear is hurting anyone with his powers.
- Malia hallucinated that she got caught in several steel-jawed traps, due to her fear of being hunted and caught in traps as a result of her adoptive father Henry Tate attempting to hunt and kill her when she still lived as a coyote in the woods in Season 3B.
- Lydia hallucinated that Tracy ripped out her tongue and kept her from being able to Banshee wail, as she feared being unable to help save her friends with her powers.
- Beacon Hills Memorial Hospital
- Parking Lot
- Beacon Hills Preserve
- Beacon Hills Animal Clinic
- Exam Room
- Reception Area
- Parking Lot
- McCall House
- Scott's Bedroom
- Scott's Bathroom
- Beacon Hills High School
- Mr. Yukimura's Classroom
- Boys Locker Room
- Beacon County Sheriff's Department
- Sheriff's Office
- Parrish's Apartment
- Living Room
- Yukimura House
- Kira's Bedroom
- Dread Doctors' Operating Theater
- "Blush" by SBCR, Elisa Bee & His Majesty Andre
- A montage of the McCall Pack creating their plan to protect Hayden and catch a Dread Doctor at the high school
- "Open Heart (Bonus Acoustic Mix) by Morgan Page ft Lissie
- Kira questions Scott about her role in the plan before deciding that she needs to figure out what is wrong with her before she helps anyone else. They both kiss for a long moment.
- "Drexler" by MADE IN HEIGHTS
- Noshiko performs acupuncture on Kira's back in hopes of correcting the imbalance between the Kitsune spirit and the human spirit within her.
- "Get Back Up" by The Unknown
- Scott, Lydia, Jordan, Malia, Liam, and Hayden all set up the equipment and fortify the locker room at the high school
- "Holland" by Glass Face
- Hayden worries about her new identity as a Chimera, and Liam promises that she's still Hayden and that she'll learn to control it while Scott watches from nearby
- "Pleasure" by Wurk Insoxx ft K-Mi
- Mason finds Corey drinking at Sinema. When Corey tries to kiss him, Mason grabs him by the arm and reveals that he's already healed from the scorpion bite.