On the Blue Lantern's new homeworld of Odym, Razer and Saint Walker's newest recruit Brother Warth to the Blue Lantern Corps are attempting to meditate under their mentor's guidance. Razer loses his temper with an insect and tries to smash it, but Brother Warth stops him. Saint Walker tells Razer to concentrate again on hope, and Razer wonders what there is to hope for. As they talk, a giant worm-like creature bursts out of the ground. Razer tries to use his red power ring on it only to realize yet again it won't function near a blue power ring. He leads the creature off but is quickly cornered... and Saint Walker plays a harp, calming the creature. He suggests that it was trying to play with Razer and warns the former Red Lantern that he judges too quickly.
A short time later, Hal, Kilowog, and Aya fly the interceptor to Odym and meet with Ganthet who is also living there after the Guardians banished him from Oa. The former Guardian explains that he is now helping Walker create the Blue Lantern Corps, and takes them to see Walker and his students. Aya approaches Razer and admits that she wasn't expecting him there, and Razer explains that he didn't know where he was going when he left Oa after the Red Lanterns were defeated. He hesitantly greets the others and explains that he came to Odym to study with Walker and try to overcome his anger.
Hal and Kilowog show Ganthet one of the Manhunter robots that they captured and explain that they came to him because they don't trust the other Guardians. Ganthet agrees to help but first he takes them to the ancient ruins of a temple where he has created and stored a giant blue power battery. He recites the Oath of Hope and triggers the device, and blue rays of energy spread out from the planet. The Green Lanterns and Aya realize that the power of hope has boosted their rings, just as it did during the battle with the Red Lanterns. They're unaware that it has activated the healing circuitry in the ruined Manhunter captive. It attacks Ganthet and Kilowog manages to smash it apart and they prepare to interrogate. Razer insists that it will be useless because the Manhunter robot is simply a machine. Aya listens to him with dismay.
They interrogate the Manhunter and it tells them that it has been created to eliminate evil from the universe. It defines emotions as evil and therefore destroys anyone possessing emotions. Ganthet admits that the Guardians programmed them that way initially but a malfunction caused them to go to extremes and commit genocide. Hal wanders if they can teach the Manhunters the difference but Razer insists that as robots, the Manhunters can't live or grow or learn. Aya wonders if Razer considers all robots as soulless creatures and Razer insists that she's different. However, she doesn't believe him and walks out.
Later, the group makes camp for the night and Razer talks privately to Walker He asks if robots have souls but Walker says that what Razer really wants to ask is if he love again after his first love died. Razer says that it doesn't matter because regardless of his feelings, Aya is a machine and can't feel love. However, Walker suggests that hope holds the answer to Razer's dilemma and will allow him to love once again.
Aya goes to the interceptor alone and steals the Manhunter wreckage. She takes it to a nearby cave and tries to convince it that they share a bond because they are both artificial constructs. The Manhunter asks why it doesn't kill those with emotions and Aya explains that she would but that she learned to overcome her programming after seeing the Green Lanterns in action. She offers to help the Manhunter overcome its programming but it refuses, insisting that its programming is intact and that it must fulfill it.
When Razer goes back to the Interceptor, he discovers that Aya has left with the Manhunter. Meanwhile, a passing patrol of three Manhunters notices the blue energy and flies to Odym to investigate. They demand the central battery and the Lanterns refuse to hand it over. The Green and Blue Lanterns are soon overpowered and Hal and Kilowog fall back to the temple to erect a barrier to keep the Manhunters away.
Aya tries to convince the Manhunter that its programming is in error but it refuses to accept her argument. When she says that it must learn to recognize and compensate for errors if it wants to become sentient, the Manhunter insists that it doesn't want to become sentient and tries to crawl toward her. Aya realizes that, unlike her, it is only a machine but the Manhunter says that the two of them are the same. It reaches for her and Aya stops it and says that she's nothing like it.
Hal and Kilowog try to hold off the three Manhunters but their energy assault starts to crack their barrier. Razer suggests that Ganthet shut down the central battery but the guardian warns that it will take several hours. As the Manhunters continue their assault, Razer gets an idea and tells Warth and Walker that he needs their help.
As Aya returns to the interceptor, she spots the energy discharge at the temple and goes to investigate.
The Manhunters break through the barrier and knock Hal and Kilowog aside. As the Manhunters fly off with the central battery, Razer has Walker play his harp, summoning the giant worm back. It swallows the central battery, smashes one Manhunter apart, and dives back into the ground. As the worm carries the central battery out of range, the Manhunters lose their boosted power and Razer tells Hal and Kilowog what happened. They renew their attack and destroy one of the two remaining Manhunters, badly damaging the other. As it falls to the ground, Aya arrives and tries to convince it to choose an alternative programming and embrace its sentience. It scans Razer and detects emotions, and then scans Aya and finds the same emotions in her. It prepares to destroy her and Razer burst into a rage, smashing it apart as his red ring comes back online. As he destroys the Manhunter, Ganthet realizes that Razer has become angry enough to overcome the blue rings' suppressive effect. Meanwhile, Razer confirms that Aya is okay and apologizes for what he said before, admitting she has more of a soul than he ever will.
Ganthet shuts down the central battery and agrees to keep it shut down until the Manhunters are taken care of. The Guardian promises Hal that regardless of whether the central battery is active, hope will always exist. As they board the interceptor, Walker suggests that Razer stay to continue his training. However, Razer tells his mentor that it is no longer necessary because he has learned that anger can be a force of righteousness when properly harnessed. Walker tells his student that he will always have a place on Odym if he wishes to return and Razer departs with his friends.