The penultimate episode of Goosebumps: The Vanishing finally reveals the truth behind Fort Jerome and Camp Nightmare... aliens!
We begin with a flashback to 1968 when the fort was functioning as a camp, previously known as Camp Nightmoon. A counselor escorts his campers to the top of the fort to look out over the ledge, but then the familiar black sludge slinks up the side of the building and snatches him up.
Back in the present, Frankie and Devin are skimming through an old yearbook for Hannah's photo. Frankie tells him their interactions were in his head, but Devin thinks helping Hannah could be the key to saving their dad.
Together, the teens' main goal is to track down Dr. Ramona Pamani, the mysterious woman we've seen everywhere who masqueraded as Trey's doctor and later took Anthony to her lab. She once appeared in an old episode of 20/20 about the 1994 vanishing, mentioning a book by her father, Dr. Avi Panami (Sendhil Ramamurthy). The teens split into groups, with Alex, Cece, and CJ heading to the library to check out the book, and Devin, Frankie, and Trey going to the hospital to find Ramona.
Elsewhere in town, Jen is trying to get into the Brewer home, with little help from Trey's dad, Joe Jr. She wants to know what's on that tape and suspects Alex is watching it with the others. She makes a call to the people tracking her ankle monitor.
At the hospital, the teens tell the nurse about the fake doctor. The nurses give them access to the security footage. They tail her to her secret lab, where Cece, Alex, and CJ meet up with them shortly after. Inside, they poke around, and Devin finds his father's shirt in a biohazard bin. Trey picks up a suitcase filled with rows of mysterious vials we later learn are serums.
But the most important find is a journal documenting all 55 years of Ramona's research and experiments.
Another flashback takes us to 1969. One year after the Camp Nightmoon counselor disappeared, Dr. Avi starts a new initiative called Project Orion underground Fort Jerome. It's revealed that inside the chamber is a sizable laboratory housing an alien spaceship. That's where all of the black sludge has been coming from and the scientists, which include Ramona and several other men, have found the counselor trapped in one of those creepy pods.
Project Orion was dedicated to finding a way to contain the ship, lest it become a threat to humanity. Their goal was to create a serum that would counteract the black sludge, and eventually, they succeeded in creating serum 429-D. There's a scene where Ramona and one of her colleagues reverse the pod creation on a lab rat.
Seeing this, Avi is ready to proceed and use the serum as a weapon on the ship, something Ramona and the others don't agree with. They think it's possible that the ship is harmless, by destroying, they're basically playing God. But Avi is determined to move forward. He sets up a rig to inject a large quantity of the serum into the ship and it seem,s to work, causing all the black stuff to dissolve and leave the thing inert.
Then, later that night, the counselor starts twitching in his pod and the ship appears to reactivate, infecting all of the scientists inside. Avi and Ramona attempt to escape, but Avi gets infected during the process, forcing Ramona to the surface and closing the chamber before she can fall victim to it, too. Back in the lab, she opens a letter from her father that tells her she must do whatever it takes to protect the human race.
Back in the present, Ramona informs the teens that she's perfected a version of the serum. That's why she was able to save Trey after his unfortunate abduction. Knowing this, Cece thinks there's still time to save Anthony, who has been in the pod this entire time. From his perspective, Anthony is trapped in a sort of mental prison identical to his basement lab. Ramona warns Cece that going back into the chamber is extremely dangerous, but Cece is determined to do what they have to in order to save their dad.
All episodes of Goosebumps: The Vanishing are now streaming on Hulu and Disney+.