At the end of the third season of The Umbrella Academy, viewers were gobsmacked when Abigail Hargreeves (Liisa Repo-Martell), wife of Sir Reginald Hargreeves (Colm Feore), had been resurrected from the dead. In past seasons, it was revealed that she had died long before Sir Reginald came to Earth (yes, they’re both aliens), and that her body was being cryogenically frozen on the moon. Reginald sent Luther Hargreeves (Tom Hopper) to the moon to protect her, unbeknownst to Luther, as he thought he was just on the moon for some science experiments. With all these references to Abigail, it seemed clear she had a bigger role in the puzzle. After fans speculated and speculated, her part in the grand unraveling of the universe is finally revealed in the fourth and final season.

Abigail created the substance, called marigold, that caused the Hargreeves’ biological mothers to give birth after Reginald brought it to the Earth from their home planet. It’s also responsible for the kids’ superpowers. When she made this, she also inadvertently created another potion, durango. When combined, marigold and durango will bring about the Cleanse, which zaps away any additional timelines and returns the world to its correct, original order. Thus, anyone who is not in the “correct” timeline will not only die but cease to exist.

In this season’s timeline, and the one the Hargreeves are trapped in, Abigail finds it to be her mission to help bring about the Cleanse. She knows this timeline where she’s alive is not supposed to exist. She is supposed to be dead, and she is resentful to Reginald for bringing her back to life here.

Thus, she poses as Sy Grossman (David Cross), saying she “lost her daughter,” Jennifer (Victoria Sawal), and encourages the Hargreeves siblings to go to New Grumpson, Maine, to save her. There’s durango in Jennifer’s system, so if she comes into contact with any of the Hargreeves siblings, the Cleanse will occur. Later, after Jennifer is kidnapped by Jean (Megan Mullally) and Gene Thibedeau (Nick Offerman), she poses as Sy again and convinces Ben Hargreeves (Justin H. Min) to chase after her, making sure that durango and marigold come together.

The Hargreeves children first meet Abigail in her actual form (not as Sy Grossman) at her and Reginald’s mansion after they were almost killed by Reginald’s militia in New Grumpson, Maine. The militia was protecting Jennifer, and Reginald had set up the village to make sure the marigold and durango never came into contact. The siblings think they’re walking into a fight and dismantled the whole town, however Abigail welcomes them into her home with open arms and plays the violin that was given to Viktor after she originally died. She knows all of the children and their old timelines, who have now settled into this timeline comfortably. She’s also softened Reginald, and convinces him to help them remember Ben’s death, which is key to understanding the world and what’s going on.

After she develops relationships with the children and encourages them chase after Ben and Jennifer, she finds Jean and Gene. There, Abigail kills Gene and takes over his skin, hoping to work from inside their cult of followers to bring about the Cleanse even faster.

Jean and Gene (who is now actually Abigail), succeed at bringing Ben and Jennifer together, and thus, no matter the efforts of the Hargreeves children, the Cleanse ensues. Abigail, still dressed as Gene, walks over to Reginald and sits by him as the Cleanse monster, a scary, beast-like creature, eats the whole world. Reginald asks Gene/Abigail if they know what they’ve done, and Abigail finally reveals herself, zipping off Gene’s skin and grabbing Reginald’s hand, proud that she ended the world.

Abigail says she had no other choice. When she originally created the marigold and durango, she believed dying was her penance for creating something so deadly, knowing it would not only bring the end of the world, but also the end of a variety of timelines. She asks Reginald why he brought the marigold here from their planet after seeing their own world destroyed, as Reginald knew the marigold could destroy the earth, too. He doesn’t have a great answer, and then she asks Reginald why he brought her back to life in this timeline. Reginald says it was an act of love, but Abigail replies, “It was hubris.” His actions had consequences—which led to all of the incorrect timelines being created—and she decided she had to set everything right. Bringing about the Cleanse was the only solution.

Abigail and Reginald are then taken by the monster, giving into the Cleanse. Abigail is the reason the Cleanse happened, and without her work, the Hargreeves children couldn’t have brought the world back to its original timeline. Thus, Abigail both ended and saved the world.