|“|| Lydia: "We opened a door to another world... And something came out with us. Now we need the Hellhound to stop it."|
Malia: "So we put it back. We've put things back before. Why are you two looking at each other like there's something you know that I don't know?"
Scott: "It might not be that simple."
Lydia: "We saved Stiles and brought everybody back, but that's not the way its supposed to happen. There's always a price to pay."
Scott: "We learned that from the Nemeton."
- Tyler Posey as Scott McCall
- Dylan O'Brien as Stiles Stilinski
- Holland Roden as Lydia Martin
- Shelley Hennig as Malia Tate
- Dylan Sprayberry as Liam Dunbar
- Linden Ashby as Noah Stilinski
- Melissa Ponzio as Melissa McCall
- JR Bourne as Chris Argent (credit only)
- Orny Adams as Coach Bobby Finstock
- Ryan Kelley as Jordan Parrish
- Khylin Rhambo as Mason Hewitt
- Michael Johnston as Corey Bryant
- John Posey as Conrad Fenris
- Susan Walters as Natalie Martin
- Claire Bryétt Andrew as Sydney
- Casey Deidrick as Halwyn
- Froy Gutierrez as Nolan
- Sibongile Miambo as Tamora Monroe
- Natalie Martin appeared in this episode. She was last seen in Memory Found.
- Conrad Fenris appeared in this episode after a long disappearance. He was last seen in Season 5A's A Novel Approach, and last mentioned in Season 5B's Amplification.
- Hayden was mentioned by Mason and Liam when they reference that she left town to protect her sister, Valerie Clark, from the supernatural. Hayden was last seen in Riders of the Storm and Valerie was last seen in Memory Lost.
- Coach Bobby Finstock and Sydney appeared in this episode. They were last seen in Relics.
- Derek Hale is seen in video footage shown by a FBI agent who reveals that he is wanted for mass murder. He was last seen in Season 4's Smoke and Mirrors and last mentioned in Season 5A's Creatures of the Night.
- Liam loses control of his transformation in this episode. He was last seen struggling to maintain in his human form in Season 5A's Creatures of the Night and learned to mostly control his Werewolf transformation in Season 4's Smoke and Mirrors.
- Liam uses Satomi Ito's pack's mantra to help him stay in human form. Satomi was last seen in Season 4's Monstrous and last mentioned in Season 5A's Dreamcatchers.
- A new, mysterious creature associated with the Wild Hunt, spiders, and rats, seemingly escaped from the Phantom Train Station when the McCall Pack opened a Rift to save Stiles Stilinski. They opened this Rift at the end of Memory Found and the beginning of Riders on the Storm.
- It is revealed that Stiles is currently doing an internship with the FBI. It was first revealed that Stiles intended to go to college to become an FBI agent in Riders on the Storm.
- Stiles left Scott a note in the Jeep that read "Be gentle." Stiles gave the Jeep to Scott to watch over while he's in college in Riders on the Storm.
- Several objects came into play in this episode that will likely be important in future episodes:
- Tamora Monroe revealed that she not only had ammunition with the Argent Family fleur-de-lis stamped on it, which has not been seen since Season 4's I.E.D., but she also had several vials of a yellow-brown serum that were seemingly used to coat the bullets.
- Lydia gave her mother, Natalie, a list of all of the supernaturals in Beacon Hills, including the ones at the high school.
- Both Jordan and Lydia experience Premonitions in this episode of the coming threats. Jordan last had a premonition in Season 5's The Last Chimera, while Lydia last had a premonition in Season 6A's Ghosted.
- Halwyn seemed to believe that Liam was the mysterious creature that he was hunting, or at the very least possessed by it, until he realized he was mistaken. This could potentially be due to the fact that Liam was able to go through the rift to the Wild Hunt while riding one of the Ghost Riders' horses in Season 6A's Riders on the Storm.
- The video footage of Derek running through the woods, is stock footage from Season 1's episode The Tell after Derek escapes from Kate.
- The title is a reference to Mary Howitt’s poem The Spider and the Fly. First published in 1829, the work stands as a warning to avoid the seductive allure of flattery and charm.
- It's revealed that Stiles went to Quantico, Virginia at FBI headquarters for his internship.
- It's revealed that Tamora Monroe was hired to be the guidance counselor of Beacon Hills High School, and that she is not only a Hunter, but has removed all books about mythology, folklore and superstition from the library.
- Mason and Corey mention that they're thinking about going to the University of California, Los Angeles after graduation.
- It is revealed that Halwyn, a Hellhound, has been a prisoner in Eichen House's supernatural wing since 1912.
- Mason makes a reference to a "rat king" when he and Liam discover a pile of dead rats with their tails stuck together in the Underground Tunnels. The phenomenon is associated with Germany (where a "rat king" is called "Rattenkönig," and occasionally in France (where it is known as a "roi des rats.") Because this phenomenon occurs so rarely, it is often believed to be a cryptid; in folklore, "rat kings" are associated with a number of different superstitions and are commonly seen as a omen of impending bad events such as plagues. Rat kings are commonly formed from black rats, though it has been shown to happen with forest mice and other tailed rodents.
- It is implied that the new creature associated with spiders and rats has the power to manipulate emotions by causing such intense fear in its victims that they begin taking pleasure in harming and killing each other and use this fear to blame the McCall Pack for the supernatural disasters in Beacon Hills.
- Although it seems that Halwyn was killed by Tamora Monroe, in Genotype is revealed that he survived.
- Dozens of wolves and rats - eaten inside out by spiders; killed by Anuk-ite
- Eichen House orderly - burned to death; killed by Halwyn.
- Beacon Hills High School
- Lacrosse Field
- Locker Room
- Ms. Monroe's Office
- Ms. Flemming's Classroom
- Principal's Office
- Entrance Hall
- Parking Lot
- Beacon Hills Preserve
- Tate Ranch
- Malia's Bedroom
- McCall House
- Scott's Bedroom
- Eichen House
- Supernatural Ward
- Halwyn's Room
- Supernatural Ward
- Underground Tunnels
- Beacon Hills Memorial Hospital
- Emergency Room Lobby
- Beacon County Sheriff's Station
- Federal Bureau of Investigations Headquarters
- Conference Room
- "Feel" by Tony Romera
- Scott and Coach Finstock lead lacrosse practice at the high school while Mason and Corey try to cheer Liam up after Hayden left Beacon Hills
- "No Apologies" by Big Gigantic ft. Natalie Cressman
- Lydia attempts to gain Malia's assistance in the case of the dead rats in the sewers, but Malia is too excited to be leaving for Paris to be interested
- "My Own Sun" by Fakear
- Ms. Monroe assists Liam, Corey, and Mason in registering for classes while simultaneously trying to gain information about the supernatural events of Beacon Hills from them and another student, Nolan
- "Gun-Shot Soldier (Scissorbox Remix)" by Sorne
- Scott and Lydia fill Malia in on what they know about the escaped creature from Eichen House. Halwyn, wounded from his battle with Parrish, runs to the woods to recover, where he is seemingly killed by Ms. Monroe. Scott, Lydia, and Malia find his body shortly afterward