Damian Darhk tosses Curtis aside and chokes Donna to force Felicity to reactivate Rubicon. Felicity reminds him that Rubicon is off-line, and threatening her mother means nothing if the world is destroyed. Darhk nevertheless begins draining the life from Donna before Oliver and Diggle burst in from the window to stop him. Oliver fires an explosive arrow, but the explosion disintegrates under Darhk’s stronger power. He sends the ghosts to fire against the two, but they manage to evade the onslaught. Just as Oliver is about to strike, Darhk stops him and begins to drain his life as well. Just then, Thea appears with Darhk’s daughter. She threatens to kill the girl unless he releases Oliver. Darhk relents his attack and escapes with his army and daughter. Unfortunately, Felicity notices that the laptop containing the anti-Rubicon code. For now, the team rushes Curtis to the lair to check on his condition.
On the island, Reiter shoots Oliver in the leg and goes after Taiana. He insists that he can take the power as the runes on his arms prevent the idol from taking over his mind. Taiana nevertheless threatens to kill him. Oliver also points out the plane leaving island, removing all of the prisoners from his grasp. Reiter, however, uses his power to cause the plane to explode, absorbing the power from their deaths. Taiana also absorbs the power and finally attacks Reiter.
Darhk: I know you don’t live here anymore, but those were nice windows.
In the lair, Curtis’ status remains stable, despite the situation on the outside looking bleak. Felicity questions Oliver on why Darhk’s magic affected him this time. Oliver responds that the hope he felt from Felicity is no longer strong enough to fend off Darhk. With Rubicon off-line and unable to be tracked, he is beginning to lose hope in winning himself. Lyla arrives to learn of the news as she tries to help Felicity stop Darhk’s plot. She questions why he would want to destroy the world since the bunker was destroyed, but Oliver replies that even Darhk has lost hope. Fortunately, Felicity believes that she has tracked the GPS of the laptop, allowing them to find it and save the world.
Oliver, Thea, and Diggle enter an office but only find the tracker instead of the laptop. A screen on the wall then lights up and displays the nuclear pattern. With the plan in motion, Felicity notes that they have approximately two hours before destruction.
The team regroups at the base to work on the new crisis. Lyla informs ARGUS to contact the president on the nuclear issue in order to warn the public. From the data, Felicity detects over 15,000 nuclear missiles to be launched worldwide. Even worse, she finds that a missile aimed for Star City has been sent out earlier, giving the city only forty-five minutes before its destruction.
On the island, Reiter and Taiana continue to fight. Reiter flings Oliver aside as he tries to help and then proceeds to drain the life from Taiana. However, the draining then turns on him as Taiana fights against it. She then sucks the life from him, causing him to be destroyed.
Back at the lair, Lance arrives after receiving a call from Felicity. She quickly advises him to take Donna on a route out of the city since she trusts him to keep her mother safe. Meanwhile, Lyla and Diggle say their goodbyes to their daughter, acknowledging that they can at least be together if the worst should happen. Diggle also laments how he has lost hope, something that Lyla believes came from Andy’s death. She tries to remind him how the death was self-defense, not knowing the truth, but they are interrupted by an ARGUS team successfully infiltrating city hall, the site of Darhk’s power. Oliver advises against sending the team who has no chance of defeating Darhk’s power now, but Lyla insists they take the opportunity. The ARGUS team corner Darhk with his daughter in the Nexus Chamber but immediately falter under his magic to the horror of the team listening to the events. Moments later, the lair is soon invaded by ghosts. With the return of Malcolm, the team manages to fight off the army despite Diggle being haunted by the image of Andy in a cornered ghost, but the lair is destroyed.
Taiana begins attacking Oliver herself, furious at him for killing her brother. Oliver pleads with her to keep control to fight the darkness. She manages to break from her rage, but she fears the hold the darkness has on her. With that fear, she pleads for Oliver to kill her.
Despite defeating the ghosts, they have approximately twenty-seven minutes before the nuclear warhead hits the city. As Oliver helps Felicity clean the base, she reminisces on Laurel when they find her Black Canary suit, how she wouldn’t want them to give in now. Oliver, however, feels disheartened that his efforts to unite the city against Darhk had failed, wondering whether or not Laurel would have lived if he stayed out of the city altogether. Curtis then hears them talking and offers his own view. He recalls his husband Paul’s incessant comments on the dangers of the city after three terrorist attacks, leading to them wanting to move. However, they changed their mind when they saw the Green Arrow on their screen, inspiring the people. Curtis states that, while it takes a special tenacity to live in Star City, the citizens prove their spirit and strength by surviving. He believes, even now, that the Green Arrow can inspire people.
With this in mind, Oliver enters the city as himself while the people resort to chaos. He stands among them and reminds the people that despite their fears, they have survived disasters in the past. Using Curtis’ words, he encourages the people to hold on to their hope that they will survive because this is their city. They are worth defending by standing united.
Oliver: I know what you're feeling right now! I'm feeling it too. It's a sense of helplessness, of hopelessness. I don't know how we even begin to process what might happen to us right now. But there are a few things that I do know. I know that this city has been through tough times before and we have pulled through. We survived the Undertaking. We survived the siege. We survived the outbreak, and somehow, someway, we will survive this! A friend of mine told me that living in Star City takes a special kind of tenacity, but we do live here. Because this is our home. …We will look to each other for hope. We will cling to each other for strength. If we do that, no matter what happens, we can all stand here, united.
In the lair, the team spots the nuke headed to the city. By seeing the nuke, Curtis then theorizes that they can now affect its path. The two move to the roof where they track the missile’s GPS signal for Felicity to upload a code to set the missile on a different path. With the code also programmed to make the missile think it already exploded, the nuke passes the city harmlessly to the surprise and relief of the city.
The two return to the lair. Although they have stopped the missile for Star City, they still need to stop more than 15,000 worldwide. By uploading the code, fortunately, Felicity and Curtis found a way to hack into the main computers for the missiles. From there, they can devise a code to divert the missiles like before throughout the world, using Lyla’s connections to enforce it. Still, they need to locate Darhk’s hacker to ensure that the missiles can be shut down. She tracks Cooper’s source while Oliver lays down the plan. He orders Diggle, Malcolm, and Thea to protect Curtis and Felicity as they find Cooper’s whereabouts while he will go after Darhk himself. Diggle protests that he will go with Oliver, but Oliver insists that he needs to make sure they are safe. Diggle reminds him that his speech inspired all of them as well.
Taiana continues to beg Oliver to kill her, something he refuses to do. She pleads that she fears killing him and everyone on the island by becoming worse than Reiter, and, if he ever cared for her, he would do it out of mercy. Before he acts, she reminds him to keep his promise to return to her home in Russia which he agrees to fulfill. Oliver then snaps her neck, only to be found by fellow prisoners.
Diggle prepares to go out in the field, but Lyla then questions him about freezing in the field. She asks if it was because of Andy, leading him to reveal that he killed Andy in cold-blood rather than self-defense. Lyla understands that it was in the fog of war and refuses to blame him for what happened, stating that he had to kill his brother. Diggle, however, cannot see past what he had to do.
Oliver confronts Darhk in the Nexus Chamber, beginning a fight that spills into the streets. Darhk easily overpowers him with his magic while the rest of the team move Curtis and Felicity to the source. Darhk mocks Oliver’s attempts to stop the end of the world but is stopped by the citizens themselves defending the Green Arrow. He further taunts the crowd, reminding them that they were ready to tear the city apart in their chaos. He tosses them aside and insists that he is providing a mercy killing for a feckless world. Nevertheless, Oliver stands up and says that he will defeat him because, this time, he is not fighting alone. The people stand up behind Darhk. Oliver fires an arrow that finally grazes Darhk’s face. He is now immune to Darhk’s magic with the hope of the people of Star City. Darhk then fights Oliver hand to hand with the city cheering their hero.
Felicity and Curtis find Cooper setting the code for the missiles while bleeding in the process. He reveals that Darhk fired a bullet at him and is slowly moving that bullet to his spine. If he moves away from the computer, he will be killed. Felicity advises him to be the man she loved seven years ago and fulfill his goal of saving the world by helping her disarm the missiles. Inspired by Felicity, he releases himself, causing Darhk to sense and kill him. Felicity then works to disarm the missiles herself.
The fight continues with Darhk nearly killing Oliver before being stopped by Diggle and Lyla who decided to save their friend despite the risk. Darhk then reveals an army of his own as ghost pour in to fight. The citizens then move to fight the ghosts as Oliver further fights Darhk.
Felicity has three minutes to disrupt the multitude of missiles despite having no way of changing their paths. Curtis then suggests that instead of disrupting the war head, they should go after the missile itself. Felicity and Curtis send out codes to order the missiles to explode before they hit their targets, saving the world from a nuclear death.
Darhk then grabs hold of Oliver’s bow and fires an arrow into Oliver’s chest. Oliver is then helped by a returning Lance. He states that Donna is safe, but he had to protect his city after hearing Oliver Queen’s speech. Oliver orders Diggle, Lance, and Lyla to fight off the ghosts to help the people while he takes on Darhk himself.
Lance: That Oliver Queen guy gives a hell of a speech.
Oliver finally corners Darhk with an arrow. Darhk tells him to stop posturing, believing that Oliver will not killing him after sparing the life of the man who killed even his own mother. Oliver, however, points out that Darhk had killed not only his friend but tens of thousands of people. While he made a choice regarding Slade, he has no choice here. Oliver stabs Darhk, defeating him once and for all.
The team returns to the destroyed lair as they ponder their future. Lance reveals that he plans to leave the city with Donna since his suspension from the force was made permanent. However, he admits that he did not feel a loss from losing his job and believes that leaving the city will give him a new perspective. Following that, Thea also admits that she wants to leave the city. After her recent threat to kill a little girl, she believes that she needs to leave to discover her real self, something Laurel would want her to do. Thea exits, leaving the original Team Arrow alone in the lair. Despite the reunion, Diggle admits that he may have to leave as well after the things he had been through so far. Oliver argues that Diggle has been the moral support since he began, but Diggle says that Oliver has been the bigger support recently.
On the island, Oliver explains that Taiana was overpowered by the idol, forcing him to kill her after she begged. He also clarifies that Reiter was the one who took out the plane, but Oliver believes there’s another way off the island. After burying Taiana, Oliver once again meets up with Amanda Waller who received his alert on the link he had returning to the island. She commends him on completing his mission and stopping Reiter’s force, saving many lives. Oliver rejects that, remembering that he took a few lives in the process. Waller explains that the situation demanded the darkness that was always a part of him, and sometimes justice requires killing. ARGUS confiscates the idol, but Waller returns a package to Oliver containing his hood, bow, and book of names. She offers to utilize his skills for ARGUS or have him return to his life as a vigilante. Oliver instead asks to fulfill a promise.
Oliver speaks to Laurel’s grave about how he killed Darhk. Although he believes it was not what she would have wanted, he apologizes for having to kill him. Felicity comes and asks about how he feels. Oliver admits that he doesn’t think he could defeat the darkness within him, but Felicity believes it is just a conflict within him, one between the man who killed Darhk and the man who inspired the city to fight. Inside him is a schism between the light and the dark, something that he needs to fight to maintain. Suddenly, Oliver receives a call from Thomas Kemp, a member of the city council who was interested in Oliver’s display to the city and asks for a meeting.
Oliver returns to city hall where, after Oliver’s display as well as his massive support as a write-in candidate, he is about to be sworn in as interim mayor. As he recites the oath to the public, the others prepare to leave the city. Lance drives out with Donna. Thea sits in Laurel’s old apartment, pondering where to go. Diggle packs his things and says his goodbyes to Lyla and Sara before returning to his military role.