Alarm goes off in a Russian missile attack warning center. Nuclear missiles are being armed.

Felicity reports about the nuclear missile situation. She makes snarky comments about Rubicon and its existence. Says she needs help from her father to hack into Rubicon to stop Darhk's mission. 21 hours to save the world. She has trackers looking for him already.

Oliver asks to talk to Diggle privately. He tells Diggle about nexus chambers.

Thea is being held in a house under guard. Merlyn shows up. He tells her about Darhk's plan. She wants to see Alex and tells him if he doesn't cooperate she's going to annoy him until he does. He takes her to see Alex.

Donna is waiting for Lance and confronts him about an affidavit he's being asked to sign stating that he didn't know Laurel was the Black Canary. Donna doesn't like that he's going to lie, even though he explains the complexity of it all. She trusts that he'll do the right thing.

Darhk is looking for The Calculator too and sends Murmer and Brick to find him.

Arrow and Spartan are looking for him too, but he's not i the apartment Felicity directed them to. Oliver uploads video to her showing that HIVE was looking for him, but he bolted before they got to him.

Lonnie Machin is in the Darkh's ark looking for the man in charge and kills a ghost.

Diggle tells the rest of Team Arrow that, yep, Noah is the only one who can stop Rubicon. If not, Darhk wouldn't have gone after him.

Felicity is digging through Noah's directory and comes across something called Raven Spur. It sounds familiar, but she can't put her finger on it.

Flashback time! Reiter is alive and Oliver is going to hunt him down.

Donna is upset with Lance when she sees him signing the affidavit. He shows her that he's changed the wording to reflect that he did know about Laurel's alter ego.

Felicity is going to meet her mom at Palmer Tech. She runs into Mr. Dennis who is not happy she hasn't been around. She tells him there are more important things happening at the moment, and she'll get back to business as soon as she can. Donna shows up as Dennis storms off. Felicity asks her mother about Raven Spur. Donnas shares that it was a cabin her and her father used to go to and where she thinks Felicity was conceived.

Oliver and Diggle are searching some more when Oliver confronts Diggle about lying to Lyla and lectures him about it.

Diggle gets a call from Felicity as to Noah's location.

HIVE has already arrived at the cabin. Noah fights them off. Brick wants to play a game with Noah which allows for Arrow and Spartan to get there to attack.  Arrow basically lets Brick go who runs off. Felicity shows up at just the right time with the van to get her dad.

12 hours before it all ends.

She tells her dad about Rubicon He agrees and starts to work, but he needs something bigger. She needs to seal a processor from Palmer Tech.

She goes there to get it, but is stopped by Dennis and security. She's been fired by the board.

Thea finds Alex. He's still in Darhk la la land. She tries to talk him down from his vitamin high to no avail.

Merlyn shows up and tells her about Lonnie and his plan to destroy the oxygen generators. He convinces her to help him fight Lonnie or they will all die.

Felicity is back at the bunker and quite upset and what has happened. Oliver comes up with a plan to break into the Palmer Tech to get the processor they need. She has Noah in tow. They actually go on an elevator to break into her office. He tries to make small talk about father/daughter relationships.

Diggle manning video and directing them all. Oliver is in the stairwell and gets accosted. He fights them off.

Felicity is locked out and has to hack into her office because the code has been changed. She can't get the processor, but Noah can downlaod the information wirelessly. He can't get it all because security is on the way. 

They take off and Lance is at the exact door they come out waiting there for them to give them a ride.

Noah was only able to extract 90% of the processor, but it was enough to start.

Flashback! Reiter's power is strong. He and Oliver fight.

Thea and Merlyn head into a house where the generators are stored. Lonnie is there. He's tied up a couple of ghosts. Thea tries to talk to him, but Merlyn shoots him. Lonnie had explosives set up and they were able to disarm them.

Arrow shows up to watch over Noah. He starts talking to the masked man about leading a dual life. He tells Arrow that a tapeworm is in the Rubicon code and when he overrode the code, it tracked back to their location. HIVE is on the way.

Lyla, Apartan, Arrow and some soldiers prepare for HIVE's arrival.

Flashback! Reiter goes down by shots from Taiana. They grab the idol and run, but Reiter isn't dead.

14 minutes left.

Lonnie knocked out Alex. He gives Thea a lecture on not letting men control her. They fight. 

HIVE shows up and a firefight ensues at the Bunker.

Alex wakes up, but Lonnie kills him. Thea is angry and fights harder. Lonnie tells her he was just trying to liberate her.

Back at Star City, the firefight continues. Murmur breaks away and heads inside to stop Noah and Felicity who are working as fast as they can.

Murmer gets in and starts shooting. Arrow takes him down.

Felicity and dad took down all nukes except for one which is headed straight for Monument Point i the U.S. Felicity comes up with a plan to fake the missile out to divert it. Only 3 minutes left.

Too late. The missile hits, but another city where only tens of thousands died instead of millions.

Oliver figures out that the magic nexus is at city hall. He and Diggle head over there and find a secret entrance to a secret lair. Darhk is there sucking in all the death magic from the tens of thousands that died.