Fallout is the latest TV adaptation of a video game, and with it comes a lot of world-specific lore. So, we’re breaking down the main Vaults for you.

Prime Video’s Fallout is the latest television adaptation of a popular video game franchise that has become hugely successful among fans and newcomers alike. The show has garnered immense attention online, and Amazon Studios has already greenlighted season two. The post-apocalyptic show takes place in an alternate timeline in American history. This alternate timeline shares many pre-World War II milestones of our world, but diverges after that.

The Cold War didn’t unfold the way it did in real life, and instead, the fictional Great War occurred in 2077, resulting in the dropping of nuclear bombs that impacted civilization over 200 years later. So, while the show takes place in the future, it doesn’t take place in our future, but rather one reflecting the 1950s-style of futuristic science fiction.

As a result, much of what we see in the show looks as though it came straight out of a ’50s commercial, from the technology to the decaying billboards found in the Wasteland. Even the way certain characters speak sounds like they are in a ’50s movie. Especially the show’s protagonist Lucy MacLean (Ella Purnell), whose catchphrase is “okey-dokey”. Lucy and her family live in a system of interconnected underground bunkers designed to protect them from radiation and repopulate America.

The bunkers are a system of hundreds of Vaults across the country that each serve a specific purpose. The Vaults were created by a company called Vault-Tech before the war so that wealthy people would have a safe place to live if the bombs did drop. However, the show reveals that the Vaults were born for a much more sinister purpose than simply repopulating a destroyed planet. The Vaults hold all the world of Fallout’s secrets, so here are the four main Vaults and their purposes, explained:

The Purpose of Vault 33

Vault 33 is where Lucy hails from. Born and raised as a Vault dweller, Lucy has a very naive idea of America’s history, what life on the surface is like, and the Vaults themselves. Lucy, along with everyone else in Vault 33, grows up believing it is their duty to harvest corn and repopulate America. Vault 33 has established partnerships with Vaults 31 and 32 to have residents from all three marry and start families to fulfill this purpose. Their goal is to bring Reclamation Day to the surface, the day when they have finally bred enough people to bring life back to the surface.

Each Vault is run by an Overseer, and Vault 33’s Overseer is Lucy’s father, Hank (Kyle MacLachlan). Hank is from Vault 31 but married Vault 33 resident Rose (Ella Vertes) and became the Vault’s Overseer. Lucy and her brother Norm (Moises Arias) are expected to do the same by marrying someone from Vault 32, but Lucy’s marriage never truly comes to fruition after raiders from the surface impersonate Vault 32 residents and kidnap Hank. This is the catalyst for Lucy’s journey to the surface, but it turns out that Vault 33’s promise of Reclamation Day was a fabrication.

The reason for Vault 33’s existence is to breed with members of Vaults 31 and 32 to create a society of designated humans to reclaim the surface and take control. Members of all three Vaults are believed to have superior genes that will make a society of people that have the best qualities to rule the surface. Essentially, the Overseers are breeding a new population of people to govern the United States who will be able to make strategic decisions to protect their goal of ruling civilization.

The Mystery Behind Vault 32

The history of Vault 32 is far more disturbing than Vault 33’s. On Lucy’s wedding day, she is to marry Monty (Cameron Cowperthwaite), presumably a resident of 32. That belief is quickly shattered as Vault 33 is attacked and Monty tries to kill Lucy and her family. It is revealed that these are Raiders from the surface led by Lee Moldaver (Sarita Choudhury) on a mission to capture Hank. The members of Vault 33 assume that the Raiders slaughtered the members of 32 to get access to 33 and Hank.

Norm is suspicious of the entire ordeal before Lucy leaves for the surface, so he decides to investigate after she leaves. With help from their cousin, Gatekeeper Chet (Dave Register), Norm ventures into Vault 32 only to discover that the residents had been dead long before the Raiders arrived. At first glance, it appears that life was essentially the same in Vault 32, from the corn harvesting to the Reclamation Day propaganda. As they continue into the Vault, it becomes clear through writing on the walls that the members of 32 discovered the truth behind the interconnected Vaults experiment.

The bodies that Norm and Chet find have been decaying for likely years by then, making it incredibly easy for the Raiders to invade Vault 33. Some residents died trying to escape to Vault 31, while others turned to cannibalism and even possible torture after the Governing Council tried to eradicate them.

When Vault 33’s new Overseer Betty (Leslie Uggams) became suspicious that Norm knew the truth, she quickly had all the evidence wiped clean from 32 and implemented a new program to start repopulating Vault 32 by transferring members of 33.

Vault 31 Holds Vault-Tec’s Secrets

Vault 31 is where the true secrets of Vault-Tec and the Vault system lie. It is the Vault that has been running the show since before the Great War even happened. By this point in the show, we had been introduced to Bud Askins (Michael Esper), a Vice President at Vault-Tec to oversee the operations of the Societal Preservation Program, specifically the three main Vaults (31,32, and 33). To continue to manage the program and the interconnected Vault experiment for hundreds of years, Bud had his brain removed and placed into a rudimentary robot, known as Brain-on-a-Roomba, to become Vault 31’s Overseer.

Norm meets the Brain-on-a-Roomba when he enters 31, horrified that this is what guards the Vault. Bud, a.k.a the Brain-on-a-Roomba fails to stop Norm from entering a room filled with pods. Bud has no choice but to reveal that the members of Vault 31 are actually Vault-Tec employees who created the Vault system and have been overseeing it for over 200 years.

These Vault-Tech employees are cryogenically frozen for extended periods and released every few decades to become an Overseer of one of the Vaults and procreate. Vault 31 exists solely as a cryogenic chamber for selected Vault-Tec employees, such as Hank and Betty, to breed generations of Vault-Tec loyalists with specific skill sets to dominate the Wasteland on the surface.

Vault 4’s Bizarre Experimentation

Vault 4 is the least Vault-like Vault the series has introduced to us so far. Lucy and Maximus (Aaron Moten) accidentally stumble into the Vault when they fall through a trap door in an abandoned hospital when looking for medical supplies. The Vault 4 members are kind and welcoming, especially when they learn that Lucy is from Vault 33. Despite the warm welcome, Lucy quickly notices that 4 is not a typical Vault.

Overseer Benjamin (Chris Parnell) is a Cyclops who is adamant about keeping Level 12 off-limits. Lucy and Max have also been tricked into thinking they’re in a quarantine cell when it’s really a test subject containment area. Some residents have extra noses on their heads, unnaturally vibrant blue eyes, or additional eyes on their faces. It’s enough to lead Lucy to the forbidden Level 12, where she discovers dozens of pods containing women who were impregnated by a host of bizarre species and videos documenting the chaos that ensued.

Through Cooper Howards’ (Walton Goggins) advertisements for Vault-Tec, we learn that Vault 4 was made to house 80 scientists who were tasked with experimenting on human hybrid species to create radioactive-resistant creatures who could survive on the surface. This didn’t bode well, as the hybrid species retaliated on the scientists and killed everyone in the Vault. Some of the remaining members of Vault 4 are descendants of those creatures. However, the majority are Surface Dwellers who have been taken in by the community after the devastating bombing of Shady Sands, the former capital of the New California Republic.

Vault 4 acts as a safe haven for the mutant descendants and welcomes Surface Dwellers who have been displaced. Since they know the truth about Vault-Tech and the intentional Shady Sands bombing, they don’t participate in the same rituals as the other vaults. The pods on Level 12 are remnants of the scientists’ experiments that are being looked after by Vault 4 members.

Fallout is now streaming on Prime Video