WARNING: The following article contains spoilers for "Adjustment Protocol," Season 6, Episode 12 of The 100.
Ever since arriving on the faraway planet of Sanctum, the last survivors on Earth aboard the Eligius IV have had to contend with the Primes. The ruling class of the planet's main settlement of human colonists revered by the general populace as living gods, the Primes had tenuously welcomed in the first visitors from the Eligius IV into their community only for the group to quickly realize things were much more sinister than they first appeared. The Primes' insidious secret behind their apparent immortality was that they had been transferring their consciousnesses into new host bodies for generations, and now planned to include passengers from the Eligius IV in their bid to stay alive.
In the penultimate episode of Season 6, the conflict between the crew of the Eligius IV and the Primes finally boiled over for the fate of Sanctum, with chaotically violent consequences. Clarke Griffin continued to act as if she was possessed by the Prime spirit Josephine as she searched for a means within the settlement to lower its protective radioactive forcefield and discredit the Primes among the local population rather than risk an all-out war. As Clarke reveals that she has regained full control of body to her mother Abby and friends, she learns that her best chance of lowering the community's shields is by speaking with the Prime tech specialist Ryker.
The plan quickly grows awry, however, when Clarke discovers Ryker has been killed by her friend Echo in order to escape from captivity. Secretly cutting out the Prime mind drive within Ryker's neck before his body is discovered by the Prime leader Russell, Clarke isolates the Prime Priya in the town's tavern where Echo, Gaia and Miller have gone into hiding. Just as the three Eligius IV crew members plan to kill both apparent Primes, Clarke subdues Priya herself while revealing her true identity to her fugitive friends.
Forcing Priya to cooperate, Clarke is successful in lowering the shields, with the rival faction the Children of Gabriel finally entering the settlement led by Clarke's best friend Bellamy Blake. Bellamy discovers that Russell has captured Gabriel, the inspiration behind the faction, and assembled the inhabitants of the community to witness the return of the other deceased Primes. Bellamy grabs the attention of the crowd and reveals the truth behind the Primes' sinister secret to immortality as Priya is forced to confirm the lies. Before the inhabitants can rise up to overthrow the Primes, however, Russell enacts his final plan.
The beginning of Season 6 had revealed that when Sanctum's red sun eclipses, anyone caught in its light become uncontrollably violent. Russell reveals he has developed a gas grenade simulating the red sun's effects and throws it in the crowd to cover his escape. The Children of Gabriel possess gas masks to protect themselves from the grenade's effects but the assembled community quickly descends into violence, leading to Priya's death at the hands of her host body Delilah's vengeful mother.
As Clarke and Gaia take cover in the Primes' palace, Russell reveals Clarke's mother Abby has been killed to serve as the new host for the Prime Simone. Holding Madi at gunpoint to force cooperation from Raven Reyes, the assembled Primes, with Gaia and Clarke in tow still impersonating Josephine, take the Eligius IV's lander back to the orbiting spaceship where they are confronted by its crew, led by Indra.
The 100 has often featured new communities with dark secrets that threaten the wellbeing of the main characters. The Primes of Sanctum and their means of staying immortal by forcibly possessing new host bodies are the latest group of antagonists to follow this trend, serving as thrilling enemies on the new world. And, as the post-apocalyptic series moves towards its season finale, the inevitable conflict has finally come to a head.
The 100 airs on The CW Tuesdays at 9 p.m. ET/PT. The series stars Eliza Taylor, Paige Turco, Marie Avgeropoulos, Bob Morley, Henry Ian Cusick, Lindsey Morgan, Richard Harmon and Tasya Teles.