On the planet Odym, Saint Walker teaches his two students, Razer and Brother Warth, on how to meditate. Razer loses his temper when an insect stings him and he tries to crush it until Warth stops him. Walker tells Razer co concentrate on hope but the former Red Lantern wonders what there is to hope for. A giant worm-creature suddenly emerges from the ground and Razer tries to stop it with his red power ring. Nothing happens as he remembers that his ring won't work in the presence of the blue power rings. He runs off and the creature comes after him. However, Walker plays his harp and calms the creature, and suggests that it was trying to play with Razer and warns his student that he tends to judge things too quickly..
Hal, Kilowog, and Aya arrive on Odym in the Interceptor to meet with Ganthet, who has traveled there after he was banished from Oa and is now creating the Blue Lantern Corps. The Guardian introduces the two Blue Lanterns while Razer walks up and Aya goes to him. She admits that she wasn't expecting him there and Razer admits that he didn't know where he was going when he left Oa. He hesitantly greets them and explains that he came there to start anew and try to set aside his rage.
Once the introductions are done, Hal and Kilowog shows Ganthet one of the Manhunter robots they captured. Hal admits that they don't trust the other Guardians after their attempt to dissect Aya, and Ganthet agrees to do what he can. First he takes them to see the Blue Central Battery they have created. Ganthet recites the Blue Lantern's new oath, triggering the device and sending the blue light of hope across Odym... and activating the Manhunter. The Green Lanterns and Aya discover that their green power rings have become super-charged just as they did during the battle against the Red Lanterns.
As they talk, the Manhunter opens fire on the group, trying to destroy Ganthet. Hal carries the Guardian to safety and the Manhunter continues its super-powered assault Aya and the other Lanterns. Kilowog manages to smash it apart and they take the debris to the Interceptor. Ganthet suggests that the power from the blue central battery supercharged the robot's healing abilities, and Hal is ready to interrogate it. Razer points out how unlikely it is that they can interrogate a machine, much to Aya's dismay.
Aya puts the Manhunter in remedial query mode and it explains that its primary objective is to eliminate evil from the universe. It considers emotion evil and will destroy any emotions that it finds. Ganthet confirms that the Manhunters were incorrectly programmed and Hal wonders if they can teach them the difference. Razer insists that robots aren't living beings and can't live or grow. Aya asks if he considers all robots creatures without souls and Razer insists that she's different, but she says that she realizes what he meant and leaves.
Later, the Lanterns make camp for the night and Razer hears Walker playing his harp. He goes to his teacher and asks if robots can have souls. The Blue Lantern realizes that what Razer wants to know if he can love again after his first love died. Razer insists that Aya is a machine that cannot love no matter what he feels, but Saint Walker suggests that hope will leave Razer to a path that will let him love once again.
Aya secretly goes to the Interceptor and takes the Manhunter away into the wilderness. It asks why it removed her and Aya says that they share a similar concept as artificial constructs. The Manhunter wonders why it didn't kill anyone without emotions and Aya explains that she learned to overcome her programming by observing the Green Lanterns. She wants to help the Manhunter to overcome its programming as well, but it insists in reciting its mantra.
Razer returns to the Interceptor and discovers that both Aya and the Manhunter are gone.
In space, the expanding wave of blue energy strikes a passing patrol of three Manhunters and they fly toward Odym.
On the planet, Saint Walker senses the Manhunters coming. As Razer emerges from the ship to warn the others, the three super-charged Manhunters descend and order them to hand over the blue central battery. The Lanterns refuse and the Manhunters attack. Hal sends one flying away but another one strikes at him, while Warth and Walker manage to subdue a second. Kilowog fights a third while the first one returns to the attack. Hal and Kilowog are smashed into the ancient temple where the blue central battery is stored, and the Manhunters spot the battery and move in to capture their primary objective.
Aya tries to convince the Manhunter to recognize the error in its programming, but it insists that there is no error. She tells it that it must learn to recognize and compensate for errors if it wishes to become sentient, but the Manhunter says that it doesn't wish to be sentient. It tries to crawl out and fulfill its programming, and Aya realizes that it is only a machine. The Manhunter points out that they are the same and tries to grab her before it shuts down, and Aya insists that she is nothing like it.
Hal and Kilowog create a barrier to protect the blue central battery but the two remaining Manhunters immediately begin breaking through it. Ganthet warns Razer that it will take several hours to shut down the central battery. The Third Manhunter arrives, adding its power to the others, and Razer gets an idea. As Warth and Walker arrive, Razer tells them that he needs their help.
Aya spots the power blasts in the distance and comes to investigate.
Hal and Kilowog's barrier gives out and two of the Manhunters depart with the central battery while the third one maintains fire on Hal and Kilowog. Razer puts his plan into action and Walker plays his harp, summoning the worm. It swallows the central battery and crushes one Manhunter. As the worm retreats into the earth, the Manhunters revert to their normal power levels. As they fire into the hole, Razer explains to Hal and Kilowog what happened.
The Lanterns return to the attack, destroy one Manhunter, and smash the second one down. It realizes that its primary objective has failed just as Aya arrives. She suggests that it can choose alternative programming as an artificial life form. It scans Razer and detects emotions, and finds similar emotions in Aya. It opens fire on her and Razer manages to access the power of his ring as he flies into a rage. He smashes the Manhunter apart as Ganthet realizes that Razer's rage has grown strong enough to overcome the blue rings' influence. Meanwhile, Razer goes to Aya and confirms that she's okay. He apologizes for what he said earlier and admits that she has more of a soul than he does.
Ganthet eventually shuts down the blue central battery and warns that it will take time to recharge enough power to reactivate it. Hal advises him to keep it off until the Manhunter problem is solved and the former Guardian agrees. However, he assures Hal that hope will always remain. As they prepare to depart, Walker suggests that Razer stay to continue his training. However, Razer says that there are many forms of rage and in his case, his anger was righteous. Walker assures him that he will always have a place with them if he wishes and Razer leaves with Aya and the others.