Oliver rallies his team as Slade's army attacks Starling City.

Felicity gets a call from S.T.A.R. Labs with news that might be game changing.

Thea comes face to face with her birth father.

Oliver walks Laurel through how to shoot her way out of the debris with an explosive arrow. Clever camera work reveals they were separated in the blast.

Ravager taunts Diggle to kill her again and asks if he'll save her time and tell her where Felicity is so she can put a bullet in her smug little face. Felicity hits her with a car.

Sebastian Blood assures the DA the men in masks are human and together they'll save the city.

Flashback: Sara is gone, Slade must have taken her. The Amazo is moving. Oliver wants to torpedo it if he's not back in an hour.

Thea is running in a throng of people at the station, and her daddy comes by to save her.

S.T.A.R. Labs has a cure and a courier is en route. He's been hit by the masked marauders and it's a race to see who gets to him first.

Oliver continues to worry about Laurel, but Felicity assures her she'll be fine.

The Chief of Police is dead and Lance wants to call the Arrow. The Lieutenant then promotes him back to detective and says he's in charge of the operation.

Laurel is in trouble and Canary shows up. Laurel hugs Sara.

A mask comes in and wants to snap the DA's neck. Sebastian says he is the mayor of the city and he's in control. She dies and he realizes he is nobody.

Lance calls the Arrow. Diggle is driving a van through the city and the masks overturn it. He, Oliver and Felicity are surrounded.

Felicity is hurt and Oliver carries her away.

Thea runs from Malcolm. He reaches out to her.

Laurel and Sara talk about redemption.

Flashback: Oliver tries to save Slade while Sara asks to please just let her go home.

The cure was found and they can't make more. Oliver tells Felicity everything is his fault.

Sara rushes into a burning, exploding building and saves a little girl. Laurel is so proud of her sister.

Malcolm is still protecting Thea. 

Sebastian Blood calls Oliver. He has the cure.

Felicity worries Oliver and Diggle are walking into a trap.

Blood tries to redeem himself by telling him about his horrible childhood and the dawn of the mask.

Sebastian tells Oliver the one person who has to die is whoever Oliver loves most.

Slade sends Ravager to take care of Blood. Seconds later he's dead.

Oliver wants to try the cure on Roy.

Flashback: Oliver went for the cure, but Slade already had it.

Oliver can't try the cure on Roy. 

Oliver calls Amanda to find out what ARGUS is doing. She is containing them in the city. There is a drone on the way to destroy the city. She gives him until dawn and Starling City is a crater.

Oliver gives Roy the cure.

Thea pulls a gun on Malcolm and he tells her to click off the safety.

As Malcolm is telling Thea that she still has a father, she shoots twice.