This episode of “Arrow” began with Oliver and Felicity planning to infiltrate an accountant’s office that works for the secret organization with intent to destroy the Glades. Before they depart, Felicity said Oliver was wrong for what he did to Diggle. He said that he felt justified in what he did, and Felicity had already said everything necessary to refute that argument.
The story moves to a flashback of Moira’s, while her husband Robert Queen was still alive. Robert was in a meeting with Frank, Malcolm Merlyn, and various other business men. Merlyn had lost his wife to gang violence in the Glades by this point. He believed that they should devise a plan to level the Glades, and start new, proposing that they use a prototype of a machine that can set off a gigantic earthquake, knocking down the buildings, and killing those inside. Robert was openly against the idea, but Merlyn had hopes to move forward with it.
The story shifted to the present, and Felicity acquired new information about the day of Walter’s disappearance. $2 million was removed from Moira’s bank account the day he was taken, and Felicity tracked down the accountant’s location to interrogate him and find where Walter was being hidden.
The story returns to Moira’s flashback, which expressed Merlyn’s past. He was working when he got a few calls from his wife. He was too busy to answer. By the third call, he decided to listen to the messages. They were grim, coming directly from his wife after she had been robbed and shot. She wanted her last words to be with him, as she struggled to dial his number each time he failed to answer. This is he drive for Merlyn to destroy the Glades.
The story shifted to Tommy, present day. Laurel came to the club for an answer as to why he broke up with her, and this fucker blatantly told Laurel that Oliver still loved her and that they should be together.
The plot moved to Oliver and Felicity. They planned for Felicity to go into the casino and get caught for counting cards. When taken to the security office, Oliver breaks in and nearly kills the owner for information on Walter. The near death scared Felicity because she never had to see him actually do his job.
The story moves back to a flashback of Moira’s where Robert and Frank discover that Merlyn had been buying much of the Glades over the recent months. By the time they spoke, he owned 1/3 of the Glades, intending to destroy it and eliminate himself as a suspect.
The story moves back to the present, Moira addresses Merlyn directly, and he confirms that Walter is still alive.
Oliver was listening to the conversation and decides to go get him. He fights a large amount of guards, opened Walter’s cell door while cloaked behind his hood, and released him.
There is a flashback to Oliver heading out onto the Queen’s Gambit, with Laurel on the dock before he boards the ship. Before he spoke to her, he called her sister, telling her not to come on the dock just yet, because Laurel was there. Laurel gave him the picture of him, which would be his inspiration to get off the island.
It is then revealed that Frank, against his will, put a bomb in the boat along with Merlyn.
The plot moved back to the present, where Laurel speaks to Oliver about her break up, and Oliver admits that he is still in love with Laurel.
Oliver was also heavily influenced by Felicity’s words. He went to Diggle’s house to apologize, admitting he was wrong about his mother’s actions and allowing Lawton to escape.
The next episode begins with Merlyn murdering every scientist in the Unidac Industries building that had to do with the creation seismic device, leaving no evidence of his involvement.
Walter was finally returned home, but he intended to divorce Moira.
There was a flashback to the island, where Oliver had been captured along with Shado and Slade. He is brought to Fyers’ office, and sees the man he did not untie when looking for medicine for Slade’s arm. Apparently, Oliver made the correct choice in leaving him tied up, because he did work for Fyers.
The story moved back to the present, where Oliver confronts Moira about her involvement with the organization. She denies that she would do that to her family. While they are talking, they are shot with arrows laced with medication, and are left unconscious.
The two wake up in chairs, and a man in Oliver’s green hood interrogates Moira about her involvement. It is Diggle behind the hood, making this a plan they came up with together. Moira admits to Merlyn’s plans to cause an earthquake and destroy the Glades.
The flashback moves to the island, where Fyers reveals his plan to stop all Chinese planes, stopping their trade system and destroying their economy, and planned to blame it all on Yao Fei.
The plot moves back to the present, where Felicity is unable to access Merlyn’s database, but she can go in person and steal their information. Oliver, Diggle and Felicity all go in together to get the information on the device. Oliver goes directly to Tommy while Diggle infiltrates security and drugs the guard. Felicity goes and gets the information off the computer, but is seen in the act, causing Diggle to intervene as a fake member of the security staff.
Hours pass, and Oliver realizes that the Undertaking was what is father wanted him to stop all along.
Oliver meets up with Laurel to discuss his feelings, and they kiss. However, he gave Tommy advice to try and get back with Laurel, and Tommy went to do just that, but he saw them through the window.
There is a flashback to the island, and Yao Fei makes a video claiming he is responsible for the plane attacks. Immediately after the camera stops rolling, Fyers shot him in the head.
The story returns to the present, where Oliver dresses as the Hood and attacks Merlyn. They fight, but Merlyn wins, and pulls back Oliver’s hood, discovering his identity.
The next and final episode of the season opens with Oliver tied up in a room. Merlyn tells him how he killed his father and sent Oliver to the island.
Merlyn leaves the room, and Oliver climbs the chain and frees himself.
The story shifts to Lance, who meets up with Felicity and connects her to the Hood.
Tommy is seen confronting Oliver on when he saw him with Laurel. Oliver doesn’t bother to justify the statement, but he reveals Tommy’s father having plans to destroy the Glades.
The flashback moves to the ensuing fight immediately following Yao Fei’s death. Shado boards the missile launcher, and shoots one at the camp, killing many of Fyer’s men.
While Lance was interrogating Felicity, he gets a call about the Undertaking plan to destroy the Glades.
The story moves to Merlyn and Tommy discussing the earthquake. Merlyn reveals that the plan is real, then plays the tape of his mother’s final words.
Felicity discovers that the device must be underground if it is to set off an earthquake. Oliver knows exactly where in the Glades Merlyn would place it, because it is the place Merlyn would want destroyed most; the street where Tommy’s mother was killed.
Moira holds a press conference revealing her involvement with the Undertaking, and that the plan is real. She leaves Malcolm Merlyn as the primary man behind the plan, infuriating him as he watches, helpless from his office.
Lance is given a call from the Hood about the location of the device, and he goes to disarm it.
There is an additional flashback of the island after the missile landed. Fyers comes out beneath rubble, holding Shado hostage again, but Oliver shoots him in the throat with an arrow. Shao’s head.
Diggle and Oliver plan to fight Merlyn together. This doesn’t work, as once Diggle is beaten, Oliver needs to fight him one on one. Oliver has never beaten Merlyn.
While the Glades are in panic, Roy saves a man from getting robbed, which made absolutely no sense. (Who focuses on robbery when the entire town is about to fall around you?) Thea arrives afterwards, stupidly going after him when there was going to be an earthquake.
Lance found the device, and even with Felicity’s guidance, they can’t disarm it. He calls Laurel to give his surviving daughter his final goodbye.
Meanwhile, Roy is still trying too hard to save people, and apparently he has no concept for good timing, because he should be escaping.
Oliver is losing his fight with Merlyn until his father’s voice goes through his mind, with his final word, “survive.”
Felicity is able to help Lance power down the device at the last instant. However, Merlyn planted a second device in the event of the first being disabled.
The earthquake sets off while Laurel is trying to escape. She saves her friend, but is hit with a beam that fell from the ceiling on her way out. Tommy enters, and helps her from under the beam. However, more debris falls on the way out, allowing him to save Laurel, but getting himself stuck. She helplessly cries, and they say they love each other. Oliver arrives to try and help him. He lifts the beam, but Tommy had been pierced by a sharp object straight through his chest. Tommy apologizes for his recent behavior, and Oliver forgives him. Tommy dies, and Oliver escapes the wreckage.
This was an excellent finale to a season. While Roy and Thea proved that they must be the dumbest people in the universe, Felicity proved herself capable of stopping half the force the earthquake could have had. Lance showed emotion towards losing Laurel. Oliver actually thought about someone that wasn’t himself. Laurel had to experience loos again in her life. There was also a very surprising death at the last instant. Tommy, who was the source of comic relief for a majority of the season, was Oliver’s best friend, and Laurel’s boyfriend, and he died. This was the largest death of the season, and placed will by leaving it until the end.