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Galaxy Brain is the 12th episode of Season 15. It aired on March 16, 2020.


Dean Purgatory Blade.png.png There was something about being there... It felt pure.

This episode summary is an official CW press release. It may contain errors.

Sam and Dean respond to a frantic call and together along with CastielJack, and Jody Mills (guest star Kim Rhodes), assist in an extraordinary and heartbreaking rescue. Billie (guest star Lisa Berry) surprises everyone with a visit to the bunker.


Four Weeks Ago: Earth-2

God on Earth 2.

At a Radio Shed, a woman is shopping as a clerk looks on, smiling. She tries to ignore the clerk and leaves, and he turns as Chuck comes in. Chuck looks at one of the TVs on display and the clerk assures him that they have everything. Chuck tells him that he wants an audience, and gestures to turn on the TVs as a background. He talks about how he created the world and then other worlds with different combinations and different endings.

God decides to destroy all of the other worlds.

The screens display the different worlds with the different Sams and Deans, and Chuck notes that Dean says he won't get the ending he wants. Chuck figures that he's gotten from the Sams and Deans, and could get what he wants from hundreds more. However, he admits that the real Sam and Dean challenge, disappoint, and surprise him. They're the ones, and Chuck figures that he needs less distraction, not more. He waves his hand and figures that it's time to clear the world by destroying all of the other worlds and failed spin-offs, and it's time to start canceling shows.

In Sioux Falls, in the real world, Jody is examining a dead cow when she gets a call. It's Alex, who tells her that dinner is getting cold. Jody isn't impressed, and says that she'll come home later after telling Alex that someone clubbed the cow to death. She sees an open barn door nearby and goes in to investigate. Something appears behind her with a burst of light and clubs her unconscious.

Dean, Sam, and Castiel meet in the bunker kitchen, and wonder if they're supposed to trust Death since she's been keeping Jack a secret. Sam warns that they have no idea where Jack's head is.

In the main room, Jack sees Mary and Dean's initials carved into the table. After looking at them for a moment, he goes into his old room and looks around. When he looks at himself in a mirror, Merle appears behind him and says that Death sent her, and asks what's up with Jack.

Castiel says that Jack trusts Billie, and he trusts Jack. Sam worries about the cosmic consequences, and dean figures that Billie has it all figured out. His brother point out that she wasn't right about Ma'lak Box and wishes they knew more.

Jack tells Merle that he called out to Billie when the Grigori trapped him, but Billie didn't come. Merle tells him to relax and lie low, and not use his powers under any circumstances because Chuck might find him. Sam comes to the door, knocks, and comes in. Merle is gone, and Sam asks who he was talking to. Jack says that he wasn't talking to anyone, and assures Sam that he's settling in. Sam awkwardly says that they're glad to have Jack back, and they would have helped him if he had come to them first. Jack tells him that he knows and leaves.

Dean and Castiel drink, and Castiel says that he and Kelly had faith that Jack would be good for the world. The angel knew that Jack wasn't done, and they share a toast to Castiel being right. Dean figures that revenge sounds good, but Castiel says that the important thing is Jack fulfilling his destiny. Amused, Dean figures that it sounds right to have God killed by his grandson. Jody calls Dean and says that she's in trouble, and if he doesn't come then she's dead. After she gives directions to the barn, the person threatening Jody hangs up her phone.

Dark Kaia attacking the Winchesters.

The next day, Sam and Dean arrive at the barn. They go in, guns drawn, and find Jody tied to a chair. Sam frees her, and Dark Kaia attacks the Winchesters. She knocks out Sam and tells Dean that he has something that belongs to her. Dean says that the spear broke, and his promise to get her back to the Bad Place expired when she hurt Jody.

Jody recovers and hits Dark Kaia over the head with a chair, and both brothers draw guns on her. Dean says that Jack is off-limits, and Dark Kaia tells them that she wants to go back to the Bad Place because it's dying. Dark Kaia claims that she had a dream, but Dean figures that she has a contact there that is sending info to her. Jody realizes that Kaia is talking about her counterpart, and Dark Kaia explains that they've been psychically connected their entire lives. Jody points out that her Kaia is dead, and Dark Kaia says that she didn't mean to kill her. She insists that Kaia is still alive, and has been stuck in the Bad Place the entire time. Dark Kaia explains that she left the other Kaia the tools to survive, but she can see through her eyes that the Bad Place is ending.

In the Bad Place , Kaia feeds herself. A storm comes up and Kaia goes out to investigate. She sees a storm gathering on the horizon.

Dark Kaia tells Jody and the Winchesters that she needs their help to get back to the Bad Place.

At the bunker, Castiel and Jack play Connect 4 and Jack wins. Sam comes in with Jody, and then Dean brings Dark Kaia in. Dark Kaia greets Jack, who stares at Dark Kaia in shock. They talk and Castiel insists that Jack can't help Dark Kaia. Sam agrees, but figures that they'll find another way, and Sam and Dean will hit the lore, Jody will go through the magical stores, and Castiel will call Sergei. Dark Kaia stands nearby and says that Jack could take then there now. Jack suggests that he can help in other ways, and Jody is glad to chain her up.

Once Dark Kaia is chained up a table, the others go on their missions. Jack goes through the Men of Letters books with the others, and finds a spell that could help. However, one of the components is the liver of an extinct monster, the last of which had been hunted down and killed by John Winchester. Dean sends Jack to check on Jody and Castiel, and the Winchesters figures that they don't have any way to cross to the Bad Place.

Castiel tries to reach Sergei but gets no answer. Jody has found a handful of unidentified objects but warns that it could take months to identify them. Castiel asks about Claire, and Jody says that ironically she's at Yosemite following up on a false lead on Dark Kaia. Jody warns that Claire has wanted revenge for Kaia's apparent death, and would do anything to save her. If they fail, it would shatter Claire emotionally.

As Castiel tries to call Sergei again, Jack slips away from where he's been secretly listening. He goes to Dark Kaia who says brushes off Jack's questions. Jack apologizes for being unable to do more, and Dark Kaia accuses him of pushing Kaia to go to the Bad Place. When Jack says that Kaia was in pain, Dark Kaia warns him that soon she'll die. He asks why Dark Kaia came there, and Dark Kaia admits that she envied Kaia and her "peaceful" world. She just finds empty spaces in a world to hide when it doesn't want her, and she's done with it.

Jack Dream Walking to help Dark Kaia

Dark Kaia grabs Jack's hands and begs him to help her world. Jack puts his hands to her forehead and his eyes glow. In the Bad Place, he sees the scared Kaia and then goes to the Winchesters and says that he's saving Kaia. Sam realizes that Jack dreamwalked, and Jack insists that saving Kaia is the right thing to do. Merle comes in, explains that she "piggybacked" into the bunker on Jack, and Jack explains that she's a Reaper. Merle says that she's been watching Jack screw up, and points out that he's risking the entire plan for one life. She threatens to tell Billie, and Jack tells her to go. Meanwhile, he'll open a rift to the Bad Place and Billie will be unhappy to learn the news from Merle too late. When Merle threatens to stop Jack, he invites her to try and suggests that Billie won't take the news that things went sideways on Merle's watch. Alternatively, Merle can help them to figure things out a smart way.

Merle says that the warding that Amara tore down can't be restored permanently, but she knows how to get it back up for a while to temporarily block Jack's use of powers from God. She'll have to juice it up and borrow Castiel, and that will keep them off of Chuck's radar. Castiel agrees and Sam Casts a spell to restore the warding. The spell powers the wards, and Sam prepares to leave with others and tells Dean that it feels like they're back.

Castiel asks Jody to stay with him as he watches Merle, and says that he wasn't able to make things right with Claire for what he took from her. He doesn't want Claire to lose Jody as well as Kaia. Jody realizes that Castiel is right. Castiel charges up the rune stone that Merle has brought, and Jack uses his power to open a rift to the Bad Place. First Dark Kaia and then Sam and Dean go through.

In the Bad Place, the group finds a cataclysmic storm sweeping through the world. Dark Kaia takes them to her home, and shadowy creatures surround them. Dark Kaia warns that if they fight, they'll lose. She says that they're scared of the storm. The creatures run off and Kaia leads the Winchesters on.

Kaia is huddled in her counterpart's home. The trio arrive and the Winchesters call out to Kaia. Kaia grabs a knife and comes out, and then hugs Dean when he greets her. Kaia stares angrily at her counterpart, and Sam tells Kaia that Dark Kaia helped them to find her. Dean says that they have to go, and Dark Kaia says that she's staying because she doesn't belong in their world but Kaia does. She yells at them to go, and they head back to the rift as the storm sweeps over Dark Kaia and the Bad Place, destroying that world and killing Dark Kaia.

The Winchesters and Kaia return to the bunker, and Jody hugs Kaia.

Later, Jack provides Kaia with some new clothes. He asks how she survived alone, and Kaia says that she kept reciting a nursery rhyme that her mother used to recite. The others come in and Jody invites Kaia to come back with her to Sioux Falls. She says that Claire will be there soon, and Kaia thanks the others for rescuing her.

Billie killing Merle with her scythe.

Once Jody and Kaia leave, Merle sarcastically says that saving Kaia was a victory and if Chuck had perceived them, they'd be dead. Billie kills Merle with Death's Scythe and glares at Jack, who glares back at her in shock. She points out that Jack is already bending the rules, and she was busy. Merle had one job to keep Jack in line, and she failed. Billie warns that they're only as strong as their weakest player, and Merle had to go. She says that all the worlds are dying but the Main Universe because Chuck is extinguishing the slate for the end. Having had enough of her riddles, Sam asks Billie what her plan is, and Billie that says as a Reaper that she wanted the Winchesters dead. However, Billie states Cass killed her and she became Death, she inherited Death's knowledge and library. Everyone has a book in the library, even God, and everything can die. Billie tells them that the books write themselves, and Chuck couldn't stop after he made the world.

God watches the Destruction of the Multiverse.

He needed to build himself into the framework to keep the world functioning, and no one can not even God can read their books unless Billie lets them. She says that they're all in God's book, and reminds Dean that she told him that he and Sam have work to do. She reveals that they are to be the Messengers of God's Destruction, greatly shocking them.

God destroying Earth 2 with meteors.

Chuck sits in Radio Shed and watches the worlds he's destroying on the TV screens. God approaches the sleeping clerk who wakes up to nervously ask if he's finished, and Chuck says that it takes a while to destroy some worlds and they'll need more of his attention. The worried clerk asks if Chuck will spare them, saying that he's served Chuck for weeks, and Chuck assures him that he'll be fine and that everything is fine. Chuck walks out and behind him, meteors smash down on the Radio Shed as Chuck destroys Earth 2.


Main Cast[]

Recurring Cast[]

Guest Stars[]


Featured Supernatural Beings[]



  • This is the second time that Robert Berens and Meredith Glynn collaborated to write an episode with The Future being the first one.
  • This is the first time Castiel sees Billie as the new Death.
  • This is the first time Jody has been to the Men of Letters Bunker.
  • It is confirmed that Jack still has no soul as of this episode.
  • God has started destroying other worlds.
  • While on Earth 2, God displays images of the Sam on Demon Blood killing his brother, another Dean's failed attempt to kill his Lucifer with the Colt and the alternate future Sam and Dean who were turned into vampires.
  • It is revealed that Kaia survived her wound, as her counterpart treated it before leaving her world. She is successfully rescued from the Bad Place before that universe's destruction.
  • Jack is briefly seen glancing at the Winchesters' initials carved into the table and touching Mary Winchester's in particular.
  • This is the first time that Castiel and Jack interact with Jody.
  • This is the first time that Jack meets Dark Kaia.
  • It's revealed when Amara invaded the bunker that the warding was not completely repaired. Merle calls the current warding "good enough warding," but not the "cosmic grid stuff" it had been before. She also states that the old warding cannot be fully repaired.
  • This is the first time that Billie is seen killing someone.
  • Billie states that God has a book in Death's Reading Room as God has woven himself into the fabric of the universe in order to create harmony between the worlds and for his Creation to live on after his demise. Billie calls this God's only weakness and only states that the book shows that the Winchesters and Jack are responsible for God's ultimate destruction.
  • Billie reveals that no being, not even God, can see their books in Death's Reading Room unless she lets them.
  • This episode marks the first on-screen use of Death's Scythe by an incarnation of Death. Previously, it was only used on-screen by Alastair and Dean in On The Head Of A Pin and Brother's Keeper respectively.
  • The "failed spin-offs" comment God makes during his monologue is in reference to Supernatural: Bloodlines and Supernatural: Wayward Sisters.
    • Writer Robert Berens tweeted after the episode "The arc of S1 of Wayward Sisters was always going to be broadly Dark Kaia vs the WaywardSisters, culminating in Kaia’s rescue and Dark Kaia’s tragic defeat. I always wanted to make that death right. But with limited real estate on #Supernatural I had resigned myself to Kaia just being dead. It was only by embedding it in S15 stories (Chuck, Jack’s return to the Bunker, Billie’s plan) it felt like it was possible to tie that loose end in a relevant and appropriate way."
  • In the episode the store is called "Radio Shed." This could be a pun based on "Radio Shack".
  • According to writer Robert Berens, the initial idea for the episode came from Jensen Ackles during the pre-production meeting for the season: "At the beginning of the season, Jared and Jensen spoke with the writers about the final season. Most of the convo was about the ending, but when loose ends came up Jensen made a point of wanting part 2 of the Dark Kaia spear saga. I felt it was important because Dark Kaia’s promise to Dean in 14.09 was so loaded, and we never resolved it. (The plan was to do it in S14 but it didn’t happen.) That Jensen agreed it mattered gave me some steam to push for it." "I don’t think they knew that part. I think with Jensen it came down to tracking the fact that Dean had broken a promise onscreen, wanting that resolved— mixed with, I suspect, that he’d enjoyed shooting his last fight with DK."
  • Castiel and Jack play the board game Connect Four. The scene was not originally scripted, and added by director Richard Speight Jr., who along with Misha Collins "riffed out the beat" of the scene.
  • This episode suffered the most casualties out of all the episodes in the series combined, given that Chuck destroyed most of the Multiverse.


  • Chuck/God: It's monologue time. In the beginning, it was just Me and sis. And it was fine. But I wasn't satisfied. So I made more. I created the world. But I didn't stop there. No, no, no. I got the bug! So I -- I kept creating. I made... other worlds. Different combinations, scenarios, characters. Different versions of the same characters. You know my -- "My other toys." Is that where I screwed up?
  • Clerk: Sir, this a Radio Shed.
  • Chuck/God: Dean says I'm not gonna get the ending I want. And I don't know. Maybe -- I -- I mean that shouldn't matter, right? I've gotten what I want from hundreds of Sams and Deans. I could get what I want from a hundred more. And I don't care. Those other toys, they don't -- they don't... spark joy. But Sam and Dean... the real Sam and Dean... they do. They challenge me... they disappoint me... they surprise me. They're... the ones.
  • Clerk: How 'bout a stereo?
  • Chuck/God: I don't need more! More things, more distractions? I need less. It's time to clear the board. All the other worlds, alternate realities, the subplots... the failed spin-offs... It's time to start cancelling shows.

  • Sam: Yeah, and what's your endgame, Billie? I mean, you lecture us about how important all this is, but we don't even know what you're doing. Jack's gonna kill God, right? Yeah? Great. Okay. How? What's your plan?
  • Billie: When I was a reaper, I believed in the rules. But then you killed me. And when I became Death, I inherited Death's knowledge... and Death's library. And in Death's library, everyone has a book. Even God.
  • Dean: So God can die?
  • Billie: Everything dies.

  • Castiel: I don't understand. Why would God write the blueprint to His own death?
  • Billie: He didn't. The books write themselves. After God made the world, He couldn't stop. He wanted more. But He needed to create a perfect harmony -- a Swiss watch, so this world could keep tick-tick-ticking in His absence. He had no choice but to build Himself into the framework. It's His only weakness.
  • Dean: So Chuck doesn't know what's inside the book?
  • Billie: No one can read their books unless I let them.
  • Sam: What about Jack? He's in God's book?
  • Billie: And so are you. I told you, Dean -- you and your brother have work to do. This is your destiny. You are the messengers of God's destruction.



Behind the Scenes[]


Promotional Pictures[]