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For the group of superheroes, see The Trinity.
"Reign, Purity, Pestilence, they were all created by Kryptonian witches to do one thing: kill the world. And now that they're together, they're doing that."
Kara Danvers

"Trinity" is the seventeenth episode of the third season of Supergirl, and the fifty-ninth episode overall. It aired on May 7, 2018.




Guest starring



"Trinity" begins with Lena being addressed by the DEO. Kara asks Lena how she had the option to keep Sam contained. Lena uncovers she utilized kryptonite in Sam's holding cell.

The Worldkillers have gone to Reign's Fortress of Sanctuary. The trio starts doing a custom when Sam out of nowhere awakens in the pocket measurement we saw a week ago. She's before long joined by the human modify self images of the different Worldkillers.

Lena calls James and apologizes for keeping mysteries from him. She uncovers to him that Sam is Reign. She concedes that she bombed Sam. Kara interferes with their call, making Lena guarantee she has no more kryptonite.

Kara unexpectedly has a dream of the Worldkillers playing out their custom. She discloses to the remainder of the DEO that while there isn't an end of the world in the Book of Rao, the antiquated content clarifies how the Worldkillers play out a "Favored Darkness."

They conclude that some way or another Kara needs to enter the different pocket measurement to stop the Worldkillers. They trust Brainiac-5 with utilizing his 31st innovation to attempt to communicate her cognizance into the other domain. It's concluded that both Lena and Alex will travel measurements with Kara.

Sam and Julia — the human modify sense of self of Purity — are working through the valley when the last continues seeing individuals she's murdered. Julia begins separating until Sam reminds her to take a full breath and consider another thing to occupy her psyche. Sam at that point recalls about her little girl Ruby and continues to separate herself.

After one stroke, you are at expanded hazard for another. Ensure you have the realities on strokes of obscure reason.

Kara flies to CatCo to converse with James about Lena putting away kryptonite. Kara declines to totally confide in Lena and requests that James nose about and give finding a shot if Lena has any more kryptonite.

On the Legion's boat, Alex approaches Lena about the tests she ran on Sam. Lena guarantees that Ruby is protected. Kara shows up on the boat and Brainiac-5 discloses to her that he has figured out how to communicate their consciousnesses, however the more individuals that switch domains, the more fragile they get.

Kara pulls Mon-El aside and discloses to him that on the off chance that anything begins going south, to pull Alex and Lena out of the measurement. Brainiac-5 beginnings the way toward broadcasting the three into the pocket measurement.

Kara, Lena, and Alex before long stumble upon the collection of Grace, the modify sense of self of Pestilence. She's dead.

Brainiac-5 is tallying down the time before they have a full sun oriented obscuration, which would mean the Worldkiller's custom worked, which would dive the world into haziness.

James gets ready as Guardian and with the assistance of Winn, gains admittance to Lena's lab.

In the pocket measurement, the gathering is contending about Lena's use of kryptonite when a Kryptonian Demon starts flying around them. Alex can utilize a stick to sare the evil spirit off and the trio proceeds with their quest for Sam and Julia.

They before long discover Sam and Julia, who are in a type of mental states, mumbling expressions of rubbish.

James is checking out Lena's lab when he has a difference in heart. Not having any desire to go despite her good faith, James reveals to Winn that nothing's in the lab, in spite of the fact that he doesn't look through a profoundly made sure about room.

Alex and Lena begin conversing with Sam, who comes to and acknowledges what their identity is. Sooner rather than later, Reign discovers that they're conversing with Sam and Sam's eyes turn red. Reign's had Sam in the pocket measurement.

Sam/Reign starts gagging Lena in the other domain when we discover Sam's awareness in now in Reign's body on Earth. She makes the DEO aware of the area of the Worldkiller's Fortress. Imra and Brainiac-5 haul the three out of the pocket measurement. They start to design an ambush on the Fortress.

Winn bestows Alex with another uniform and some tech.

Kara, Mon-El, Imra, J'onn, and Alex start battling the Worldkillers as Lena remains on the Legion boat to help Brainiac-5 and Winn pilot it.

Group Supergirl is getting bested when they're ready to persuade Purity/Julia to ascend against Reign and Pestilence. Epidemic cuts Purity, yet Purity utilizes her sonic forces on Pestilence, slaughtering her. Immaculateness bites the dust presently.

Their spirits are evidently consumed by Reign before the Fortress of Sanctuary starts disintegrating to the ground. Group Supergirl can get away.

Back at the DEO, Mon-El and Imra are celebrating about halting the Worldkillers. They choose it's an ideal opportunity to return home. Imra leaves the room and Mon-El seems to think again.

Kara shows up and tells J'onn and Alex that the Fortress of Sanctuary has deteriorated, however Reign/Sam is mysteriously gone. Winn discloses to Kara that he and James looked through Lena's lab and discovered no additional hints of kryptonite.

Hearing the phony news, Kara approaches Lena and discloses to her that their record is spotless.

Lena converses with James at CatCo. James concedes that he initially thought Lena was a carbon copy of Lex yet in the course of recent years, she's kept on refuting him. James uncovers to Lena that he's Guardian. He reveals to her that he broke into her lab on Supergirl's requests. He reveals to her he didn't go into her vault since he confides in her.

The two embrace and Lena reveals the kryptonite wasn't her brother's; she discovered how to make it.

The episode ends with Reign hovering over the city, receiving a message from Selena that "Ruby Arias must die." At the same time in Juru, Sam touches her daughter's name and screams.




  • The episode's title refers to the Worldkillers - Reign, Purity, and Pestilence.
  • This is the third episode of Supergirl where Kara appears only as Supergirl, the first two being "Resist" and "Of Two Minds".
  • One of the names Julia writes in the cave is "Peter David". Peter David was a writer of the Supergirl comics for many years.


  • Katie McGrath slips into her native Irish accent at several points throughout this episode.