Blight is causing havoc, as the Mayor, Chief of Police and several others come down with bloody noses and fevers.

Brainy purchases an image inducer to blend in while out and about in National City. It startles the others at the DEO, but Winn isn’t phased in the slightest.

Meanwhile, Sam is electrically shocked at 500 watts in the hopes of bringing out Reign. This of course brings Sam face to face with Reign inside the dark valley scene we’ve witnessed a few times this season inside Sam’s dreams.

Those currently affected were quarantined inside a government building. After careful examination, scratch marks were determined to be the catalyst for the infection, similar to what Agent Danvers had observed back at the lab with the birds.

After a doctor revealed to them that the quarantine had to be lifted, Alex and Winn reassured her that a cure for the disease would be found soon. As Kara and J’onn were headed out, ready to fly the sicked patients to a trauma ward, all hell broke loose.

Imra decided placing a forcefield around the hospital was necessary. Her , of course, judgement call caused a spat between herself and Supergirl, who insisted the forcefield be taken down. Their tension is sure to cause more problems in the future. 

Sam’s mind “literally goes there” as she enters the dark valley. Lena is still exploring the cause of Sam’s transformation into Reign.

Imra and Mon-El speak as his wife’s body is scanned for anomalies and symptoms. Coming up without any symptoms, Imra remains insistent that killing Pestilence is the only way to avoid Blight wreaking havoc in the Legion’s future.

A cure is developed by Brainy and Winn. It’s set to be distributed soon to patients who were initially infected. Alex tries to convince Kara that Imra needs some more convincing. I savor any and all Danvers sisters moments like these.

Winn rushes in out of breath with his suspect: Adelaide Swanson. Since she seems to be the only person terrified at city hall not showing symptoms, Supergirl is sent to her residence to investigate. She’s greeted by Imra, suspecting the Legion member to have hurt Adelaide. Instead, Adelaide is fatally wounded by Pestilence. 

Kara is floored by the fact that Imra felt it necessary to sneak behind the DEO’s back and come to Adelaide’s place before them. She’s not building any more trust in Imra.

Winn is speaking on comms when Alex notices he’s sporting a bloody nose. He’s rushed into the med ward in the DEO, where Brainy distributes the cure to him. They still don’t know why the scratches appear on victims’ hands, only that they manifest once symptoms appear.

Kara confronts Imra at the DEO. Imra insists she’d kill Pestilence in this time to prevent millions of people from dying when the Blight happens.

Sam and Reign speak again in the dark valley. Reign attempts to convince her to surrender to her darker tendencies, to gain control back. Sam refuses electro-shock treatment, terrified to face Reign again as she comes to. After a few moments, Sam decides to continue anyways.

J’onn speaks with Supergirl, imploring her to keep trying to get through to the Worldkillers. He compares this persistence to all the mornings where he speaks with his father, whose memory is waning.

Mon-El and Imra speak on her personal reasons for the Legion’s return to 2017. It seems she has people close to her who will die if the Blight is not prevented. Mon-El agrees with Kara and doesn’t want to kill Pestilence.

The cure is not working. Winn’s shortness of breath and possible fast heartbeats confirm that. Brainy points out the reason the cure won’t work is because it was based around the strain that the Blight unleashes in the future, not the strain produced by Pestilience in the present. So it’s back to square one. They need to find a piece of Pestilence’s DNA.

Alex collapses on the ground. She’s put on bed rest, insisting that she should be helping.

“I will turn your world into ash. Especially her. Your heart, your strength. I will kill Ruby.”

Reign has made this personal, and I’m not okay with it.

Sam is distraught, imploring Lena to get help from Supergirl or the DEO to find the trigger for Reign’s taking over. Lena reminds her that Sam is safest in her lab at L-corp. Sam doesn’t want to become a government test subject, and agrees to continue the experiments in secret.

After reviewing security footage, a suspect is properly found: Doctor Grace Parker. She was on site at City Hall 24 hours before the Pestilence symptoms were discovered. Brainy tips Imra off moments after Pestilence’s identity is revealed.

Dr. Parker is seen invading a board meeting at an insurance company, flashing a claw and hazel eyes. She threatens the men in the room with violence, until Supergirl’s heat vision stops her from scratching the man.

Supergirl almost gets through to Pestilence, until Grace reminds her that all the lives lost outweigh the good she’s done as a doctor. She maintains that her godlike powers allow her to decide who lives or dies.

A fight breaks out between Supergirl, Pestilence, Imra and Mon-El. After much grappling, Supergirl is scratched by Pestilence, causing her to fall. Imra manages to trap Pestilence inside her forcefield, only to have Purity arrive to heal Grace and the two WorldKillers head off in an escape.

Luckily, Imra managed to extract enough DNA for a cure to be developed, healing all the victims Pestilence created thus far, including Alex, Supergirl and Winn.

Imra reveals to Kara that Psi got into her head on Fort Rozz. Preya, Imra’s sister, was killed during the Blight. This is what motivated Imra’s quest for vengeance against Pestilence. She blames herself for wanting to kill Pestilence, instead of redeeming her.

The two make amends as Supergirl promises to save Imra’s sister.

Purity’s frequency is detected by the DEO’s servers, and Supergirl races to protect Lena at the DEO ahead of an attack. Supergirl is agog upon seeing Sam locked away in her chamber inside L-Corps lab.

Purity and Pestilence arrive sporting new makeovers, attacking J’onn and Supergirl as Reign manages to escape. Reign escapes with the other Worldkillers, casting some spell to hold off Mon-El, Supergirl and J’onn before escaping via flight.