- For the issue of the same name, see Sacrifice (issue).
- "Because you don't know in your heart what you're fighting for, what you're willing to sacrifice and I do."
- —Malcolm explaining why Oliver can't beat him
Oliver and John race to stop Malcolm Merlyn from unleashing his vengeance on the Glades. However, they run into a roadblock after Detective Lance picks up Felicity for questioning. Tommy and Oliver’s already tumultuous relationship takes a turn for the worse after Oliver makes a confession about Laurel. After hearing of the danger in the Glades, Thea races to find Roy, inadvertently putting herself directly in the line of fire for Malcolm’s devious plan. On the island, Oliver, Slade, and Shado, are locked in a life-or-death struggle against Edward as his missiles lock on a full Ferris Air jetliner.
Malcolm imprisons Oliver, but he manages to escape and return home with Diggle's help, due to a tracker in his boot. Which John also remarks to take back his jokes about sticking tracker in the boot.
In a flashback, Edward fires a missile at an approaching airliner, but Oliver and Shado manage to override the coordinates and destroy the missile.
Felicity got caught up by Quentin and brought back to the station for interrogation.
Afterward, in a flashback it shows that Oliver killed Edward.
In the present, Oliver confronts his mother about the Undertaking, which prompts her to hold a press conference and reveal to the city her involvement with Malcolm and the plan to destroy the Glades. When Tommy confronts Oliver about his night with Laurel, Oliver tries to explain what's going on with his father and the Glades. Tommy doesn't believe him and tells his father, who reveals it's all true. Tommy sees the press conference, and Malcolm reveals that he is The Dark Archer, to the dismay of his son.
Meanwhile, Felicity has been brought in for questioning because of the all of the tasks Oliver asked her to do before he revealed he was the vigilante. She hadn't covered her tracks because she didn't realize (at the time) what she was doing was aiding and abetting. Detective Lance starts to question her, but Oliver calls as the vigilante to explain about the Undertaking and how it's going to happen tonight. Felicity hears the call and asks the Detective, if he really wants her there since it sounds like he's got something a lot bigger on his plate. Lance releases her with a warning not to leave town. Before she leaves (even though it will almost certainly confirm to Lance that she's helping the Hood) she tells him that she thought the vigilante was a bad person too, but then she realized all he was sacrificing to help the city. She posits the question, "Doesn't that make him kind of a hero?"
Lance tries to go to his boss to tell him what's going on, but it's revealed that he's had almost constant contact with the vigilante, so he's suspended. It isn't until Moira's press conference that the police get involved.
Oliver decides to go after Malcolm again, even though he knows it means he'll probably die, because he hasn't beaten him once. Diggle offers to go with him and Felicity says that leaves the bomb dismantling to her. Oliver refuses and she points out, he doesn't have any other option. He then calls Detective Lance again as a compromise. Felicity will work from the Foundry, staying in the Glades but in better shelter, Lance will deactivate the device with her help and Oliver and Diggle will go after Malcolm.
Detective Lance, with help from Felicity, is able to dismantle the earthquake device. John and Oliver (Oliver sticks an arrow through his shoulder to hit Malcolm's heart) disable Malcolm, who gloats that there is a second device shortly before he loses consciousness. The device activates and begins to level the east side of the Glades.
Thea goes into the Glades to save Roy, who works to help others who are trying to escape the earthquake. He refuses to leave the Glades when he sees a busload of people stuck because of a car accident and sends Thea away because he can't help those people if he's worried about her being caught in the Undertaking.
Laurel who went to CNRI despite warnings from both Oliver and her father, is trapped in her office when the quake starts and gets stuck under a slab of concrete but Tommy arrives to rescue her. Laurel escapes, but Tommy is caught by falling debris. Oliver arrives too late to help him, Tommy is fatally wounded and dies after apologizing and making amends to Oliver for fighting and being angry and jealous. Tommy asks if Oliver killed his father and Oliver lies to him, spending Tommy's last moments holding his hand, insisting it should have been him who died instead of Tommy.
Preparation ran from March 28 until April 8, 2013. Shooting ran from April 9 until April 18, 2013.
- Originally the episode was titled "52 Wells Street", but was changed due to sounding too "artsy".
- Unidac Industries is a reference to Unidac, a company in the TV series, Wiseguy.
- Papp Street, under which one of the Markov Devices is located, is a reference to George Papp, one of the co-creators of the character, Green Arrow.
- The abandoned subway Detective Lance enters, Puckett Station, is a reference to Kelley Puckett, one of the co-creators of Connor Hawke, who in the comics is Oliver's son and the second Green Arrow.
- As Roy is running through the Glades, a Kord Industries sign is seen. In the DC comics, Kord Industries is led by Ted Kord, the alter-ego of the superhero Blue Beetle.
- The airliner is owned by Ferris Air, a company which in the comics employs Hal Jordan, the alter-ego of Green Lantern.
- This episode marks the restart of Oliver and Tommy's friendship which ended in Unfinished Business, although Tommy dies shortly after they make amends with each other.
|"Pilot" • "Honor Thy Father" • "Lone Gunmen" • "An Innocent Man" • "Damaged" • "Legacies" • "Muse of Fire" • "Vendetta" • "Year's End" • "Burned" • "Trust but Verify" • "Vertigo" • "Betrayal" • "The Odyssey" • "Dodger" • "Dead to Rights" • "The Huntress Returns" • "Salvation" • "Unfinished Business" • "Home Invasion" • "The Undertaking" • "Darkness on the Edge of Town" • "Sacrifice"|