Supergirl Season 4 Episode 4 saw the Graves siblings, along with Jensen and the Agent of Liberty, go through with the next part of their plan -- making humans fear aliens. 

To accomplish this, they stole a parasite to mind control aliens into unleashing violence on innocent civilians using Fiona's psychic abilities. 

Following their previous attack on Supergirl, they assumed she was no longer a problem, but we know she survived using Lena's containment suit. 

Alex ordered Supergirl to stay put until she healed completely because since the suit was working overtime to filter the Kryptonite out of her body and would not be strong enough to withstand the blows.

However, Supergirl disobeyed Alex and ended up collapsing within the first few seconds of the fight. 

Back at the D.E.O, Alex received a scathing call from the President for not following explicit orders. 

Knowing her job was on the line, she let Kara have it for disobeying her and made sure she understood who was Director. 

Brainy and Lena put their brains together to come up with a plan to cleanse the air of Kryptonite. 

When she noticed Brainy was having an emotional and human breakdown, she ordered him to store his feelings into boxes and push them to the side. 

Once he did that, they were able to come up with a more permanent solution -- nanites that would suck up the Kryptonite. 

When the Graves siblings took their attacks to the National City Fair, Alex roped in Supergirl despite the President's orders. 

Supergirl was close to being killed off by Otis Graves when the filtration of the air was completed. 

She fought back but at the same time, Jensen panicked and broke the mind control over the aliens.

One of them attacked both siblings with dagger-type weapons and supposedly killed them. 

The Agent of Liberty continued on with the plan and inserted the parasite into Jensen.

Meanwhile, the President sent Colonel Hayley to look over things at the D.E.O until Alex could get a handle on them.  

J'onn got an unexpected visit from Manchester Black, Fiona's fiancee. 

They teamed up to find her but when they finally got to her at the carnival, she was on her deathbed. 

She begged Manchester not to be vengeful and angry, however, when she passed, he purchased a whole case of weapons. 

With Supergirl temporarily down, James Olsen leaped back into action as The Guardian despite warnings against it from Nia, his cub reporter. 

He went viral online, but instead of being hailed as a hero, people assumed he was anti-alien and gave him the nickname the "Guardian of Liberty."