After Adam and Kem find the probe in the outlands, they immediately contact Seg. When Seg arrives, he stops in his tracks. Brainiac seems to have already made a visit to Krypton.
They take the probe to the Fortress for Val to analyze. When they show it to Val, he knows exactly what it is. He tells them that inside the probe is a Sentry, a parasite who takes a host and gathers information about the planet. They all agree to have the probe open to see if the Sentry has escaped. When they open it, it’s empty.
The episode then flashbacks to three days earlier. A woman named Rhom (who is Kem’s sister and is also the woman who visited Seg at his house with her daughter in episode 2) finds the probe in the outlands while looking for scraps to sell in the market for money.
Seg and Adam agree to split up and look for the Sentry. Adam goes to the labor trade market, while Seg go to the Military Guild to see if anyone has turned it in.
On the way to find Lyta, Seg runs into Nyssa. She invites him to dinner. Seg appreciates the offer and expresses more gratitude for what she did for his parents. Nyssa senses Seg is holding secrets from her and tells him she has her own. Before they go their separate ways, she tells him of Lyta’s promotion to commander.
Seg confronts Lyta, expressing his fear for her safety. She tells him she did it “to change the way the Sagitari treat the Rankless”. Lyta is given her first order as Commander by the General to go in search of man with whom they think has Black Zero connections in the Rankless area. Lyta tries to convince the Head Magistrate and her mother to take lighter tactics to find the terrorist. But she is ignored. Although, before her command leaves for the Rankless area she orders her troops to not attack any of the people or they will answer to her.
While Adam roams from one vendor to another in the labor trade market, he finds the Sentry. And steals it. When Seg and Adam are on their way back to the Fortress of Solitude, they are intercepted by Lyta’s command. Seg gives the Sentry to Adam and tells him to get it to the Fortress.
After witnessing some of the Rankless being beaten up upon, he confronts Lyta:
Seg: Is this your idea of changing things?
Lyta: I am trying, but we cannot ignore the intelligence that Black Zero’s operated out of this area.
Seg: Do they look like Black Zero to you?!
Lyta: This was going to happen with or without me. I am doing my best to make it as safe as possible.
Seg: How long have you known about this? You chose not to tell me. You didn’t trust me.
Lyta: I can’t talk to you right now. Get out of here, Seg.
Kem goes in search of his sister, Rhom, and her daughter. When he finds her, she is ill. The Sentry is taking over her. She then attacks three Sagitari soldiers leaving them for dead. No one see who did it. Kem took Rhom’s daughter back to his bar for safety. The Sagitari gather all the Rankless in the area, binding some of their hands. When one of the Sagitatri gets rough with one of them, one steps forwards to try and stop her. But in the scuffle, she shoots him. When Lyta shows up, she confronts the Sagitari and has her arrested. The Rankless feel justice was finally served and obeys Lyta’s orders.
When Seg finds out Rhom is the one infected by the Sentry, he goes in search of Lyta. He has an idea to save her, but he needs Lyta’s trust and an electrostatic grenade. Lyta asks what is really going on and Seg asks her to trust him. She gives him the grenade and keeps her command out of the communications hub where Rhom is found connected to the computer. Seg tries to get through to her, using her daughter to help her fight off the Sentry. But the Sentry is found to be too strong. Seg then uses the grenade and is able to disconnect her from the computer allowing him to take her to the Fortress.
When Val analyzes her to see if she can be saved, he finds the Sentry is keeping her alive. And that she was the transmitter to Brainiac and she has already sent the information to him. He is now on his way.