On Lian Yu, Oliver realizes that he has to save the universe by ending his journey where it began: in Purgatory. Conner explains that ARGUS agents attacked them at the bunker, captured them, and brought them to the island. Lyla steps out and says that she didn't have time to convince them. She explains that Mar Novu needs them to build a weapon on the island, and Oliver says that the Monitor isn't their enemy. He explains how the Monitor dropped him in an alternate reality to teach him that to fix the Multiverse, they need to work with him. Diggle isn't convinced, and Lyla explains that Wong has been working on the weapon since Hong Kong. The device is powered by plutonium, and Dinah, Roy, and Rene are on their way with the plutonium that Ray and Diggle stole.
Oliver asks Lyla why he's back on Lian Yu, and Lyla explains that there have been energy spikes there. Harnessing the energy is the key to building the weapon, which will allow them to survive Crisis even though they can't stop it. Oliver asks for a moment alone with his kids, and once the others go, Oliver tells them that the Monitor has seen that he doesn't survive Crisis. He's trying to save the Multiverse and keep his children safe, and Mia angrily says that they'd better get to it.
Diggle goes to the ARGUS bunker with Lyla, and she explains that the Monitor required her to maintain silence. All the Monitor told her is that she'd know what to do when the time came. Lyla explains that the Monitor rescued her from the IED explosion in Afghanistan because she had a greater destiny. He came to her later and showed her their future wiped away, and she's working with him to find heroes strong enough to survive the Crisis. Diggle says that he won't accept it's the only way to move forward and walks away.
Rene, Dinah, and Roy take a plane to Lian Yu and spot the island ahead. They contact the island team, and Diggle says that they'll meet them at the airfield. Dinah spots something, and the island team report that something is incoming. They go out and see a missile slam into the plane, destroying it above Lian Yu.
Back in the tent, Oliver says that they have to find the crash site. Conner reports that something is blocking their radio signal. William confirms that the tracker in the plutonium case shows it landed far from the crash site. Diggle, Lyla, and Connor go to rescue their teammates, and Mia says that she's staying there. Oliver agrees, figuring someone needs to protect William, and leaves with Laurel.
Oliver follows a tablet with a map synced to the plutonium. He admits that he's glad Laurel is there, and Laurel wonders why Mia isn't there with Oliver. Oliver figures that Mia doesn’t want to talk to her, and Laurel says that Mia just wants to live up to her father. She advises him not to leave the island with more regrets then he already has buried there.
At the camp, William works on the weapon and notices that Mia is distracted. He asks if she's still mad their father, and Mia tells her brother that Oliver has always done whatever he wants with his life. Mia figures they should never have trusted Oliver, and goes to get a wire stripper that William needs for his work.
As they head through the jungle, Lyla tells Conner that she's glad they had time together. He says that she was there when he needed, and mentions how they founded Knightwatch. Lyla insists that the Monitor isn't evil, but Diggle doesn't believe it. They find Dinah helping an injured Rene, and they say that they have no idea what happened to Roy. Lyla takes Rene to the camp while Dinah, Diggle, and Conner search for Roy.
Oliver finds the plutonium, and a masked Billy Wintergreen comes out holding a knife to Laurel's throat. Fyers steps out with more of his men. They aim their guns at Oliver, who draws his gun. When Fyers tells him to drop it, Oliver spins and shoots Fyers' men. Laurel breaks free from her captor, and Fyers escapes in the confusion. Oliver tells Laurel to get the plutonium to William while he deals with Fyers.
Heading through the jungle, Oliver catches an arrow... fired by Yao Fei. Oliver is shocked that Yao Fei is alive, and Yao Fei warns him that there are those who don't want Oliver to succeed. Yao Fei says that Oliver must not let the evil that tempted him at the start distract him at the end. He reminds Oliver that the last time he tried to do things alone, it didn't go well.
Diggle, Conner, and Dinah find Roy badly injured on the ground. His arm is pinned by wreckage, and nearby an engine is leaking fuel. The sparks from the engine threaten to ignite the fuel, and they realize that Roy's arm is crushed. Diggle figures that they have to amputate Ray's arm to get him out, and they hear something move. Dinah goes to check it out, and Diggle and Conner look for a lever to free Roy so they don't have to amputate.
Laurel comes out of the jungle with the platinum, and Dinah tells him what happened to Roy. She explains about Fyers and his men, and how Oliver went after them. The two of them head back to Roy, where Diggle and Conner are trying to lever the wreckage off of Roy. They fail, and Diggle angrily insists that they always have a choice. Roy tells them to amputate before the fuel ignites, and Diggle reluctantly agrees while Dinah and Laurel go to take on Fyers' men who are coming. Conner cuts with a machete and Roy screams in pain.
Yao Fei says that he's helping Oliver for Shado, and Oliver regrets not saving Yao Fei's daughter. They find Fyers' camp and are caught in a net trap. Yao Fei's bow is pinned, and Oliver tries to cut the braided steel net strands with his knife.
Diggle and the others take Roy to the camp. Mia says that she and William have to go after Oliver, but the others say that it's better for them to stick together. Angry, Mia goes off on her own and William goes after her, saying that the others are right. He warns that Mia going out could make things worse and refuses to get out of her way. William tells her that it's okay for Mia to be afraid for Oliver. Mia refuses to let Oliver die, and believed for a minute that she could have her dad. Her brother says that he spent a lot of time pushing Oliver away because he never thought he could lose him, and then Oliver disappeared. William figures that they don't want to waste the time Oliver has left being angry with him, and asks Mia if she wants to.
Yao Fei tells Oliver that he's still an impatient boy, and Oliver says that he needs to get back to his family. The older man points out that he's avoiding his family because he's fated to die, and advises Oliver to say goodbye to his children. Oliver figures that he can't, and Yao Fai tells him that he lives on in Shado and that is surviving. He says that Oliver should live now with his children with the time he has left. Yao Fei then uses a magnifying glass and his knife to burn through the rope holding their nets up.
Diggle checks on Roy and apologizes for failing to find another way to get him out. He admits that he can't protect the people he cares about, and Roy tells him that the team has each other's back no matter the cost. Roy would rather be there with the team then living a life by himself. He tells Diggle that heroes make sacrifices and losing his arm was his.
Dinah and Rene confirm that Fyers and his men have surrounded the camp. William says that they can't move because he's tapped into island's energy core using the weapon. Oliver arrives and says that he should have been there with William and Mia, and tells them to activate the weapon. If the island's energy brought Fyers and the others back, then absorbing it will destroy them. Oliver figures that it's their best chance and tells the team to suit up.
As night falls, Arrow goes out and confronts Fyers. He says that he's there to kill Fyers and he's not alone. The others step out.
William tells Lyla and Roy that all he has to do is power up the weapon... and it shuts down.
Fyers' men open fire on the heroes, who run forward to attack them.
William realizes the device can only be turned on using a specific DNA code. Lyla realizes whose code is necessary, and radios Arrow to come back. Arrow says his goodbyes to Yao Fei and heads back to the camp with Diggle. When they get there, Oliver warns that the others can't hold back Fyers' men for long. Oliver picks up the weapon sphere and it shuts down. William realizes that Oliver's DNA doesn't match the sequence, but Lyla's does.
The heroes continue fighting the mercenaries, buying the others time.
Diggle realizes that Lyla is the weapon, and says that he understands why she has to do it.
The mercenaries overwhelm the team.
Lyla takes the weapon and it activates. The dwarf start device activates, and the ghosts disappear. Meanwhile, Lyla tells Diggle that she has to go, enters a breach portal, and disappears.
The next day, Oliver checks with ARGUS and confirms that they're sending a rescue boat. Diggle tells Conner that Lyla was just as surprised as the rest of them, and figures Lyla can handle whatever the Monitor has planned for them. Oliver says that they don't have long until the Crisis, and Oliver thanks Rene and Dinah for being there for him no matter what. They figure he's saying goodbye and tell him that it isn't over until it's over.
Oliver finds Roy and apologizes for losing his arm. William arrives and tells them that the rescue boat is there, and gives Roy the stone that led him there in the future. Roy says that he doesn't need it and figures that it should stay in the family, and leaves. William hands it to Oliver, who tells him to keep it. He assures his son that he's a hero, and William says that he had a good example. Oliver asks William to forgive him for lots of things, and William says that he already has. When he was a kid, he didn't understand what it meant to fight for something bigger than himself but now he does. Oliver says that he's proud of him and they hug.
Outside, Diggle tells Oliver that Lyla sacrificed herself for the Multiverse. Oliver asks him to get the kids back to 2040, and Diggle says that he'll get them home safe. After a moment, Oliver asks Diggle to find Felicity and have her keep Mia and William together. Diggle agrees and says that he feels like he's been failing him. Oliver assures him that he would never fail him, and Diggle says that he knows Oliver has to do it alone. They hug and Oliver says that there's one more thing he has to do.
Oliver goes to Yao Fei's grave, and Mia finds him. She says that she heard stories about the "legendary" Arrow and should have been proud of him because he was a hero. All she could see is that it was the reason Oliver wasn't with her, and she couldn't let it go. Oliver says that he never meant to cause her pain but he and Felicity wanted to protect her. His daughter says that she understands, and Oliver talks about how he used to hate Lian Yu for all of the people it took from him. The island taught him to survive and turned him into someone better than the person he was before, and it gave him the chance to be with his daughter. Mia thanks him for lettering her be part of his stories, and Oliver assures her that she'll create her own stories. They hug and Oliver figures that they need to go home and be prepared. Above them, the sky turns red and Lyla appears before them. She says that now she's a harbinger of things to come and the Crisis has begun.
In the sewers of Central City, Nash says that he's traveled across the Multiverse to kill the Monitor. Now the Monitor has saved his life, and the Monitor tells him to submit and begins his life anew. The runes glow and Nash touches them in sequence. The panel opens and a burst of light shoots out, bathing Nash in its radiance. He disappears, screaming.
Written by Gadfly on Dec 4, 2019