WARNING: This review contains spoilers

Season 4 of Arrow has seen the return of many past characters (even one who was technically dead), so it’s only fitting that this week’s episode brought back one of our favorites: Roy/Arsenal! Even if it was only briefly, it was great to see one of the show’s former core players back in action with the team and get some much deserved closure. And that wasn’t all! This episode also introduced a very interesting new villain, continued Thea’s post-Pit bloodlust storyline, began an intriguing subplot starring Nyssa.

The episode begins not in Star City or even in flashback on the island, but at Nanda Parbat, where Malcolm has Nyssa held prisoner. A visitor brings her food and before she can refuse it, she realizes this woman is on her side and finds a small knife hidden within the meal. Wielding that tiny weapon and she and her co-conspirator take down her guards in what can only be described as a kick-butt action scene, and more of the League reveals themselves to be loyal to her rather than Malcolm.

Later on in the episode we get another glimpse of Nyssa, this time in Japan. On her quest to become the new Ra’s Al Ghul, she is seeking the Lotus, a mysterious and rare elixir. She engages in a epic sword fight with its guardian, Katana. Realizing the two are evenly matched, Nyssa suggests they instead lay down their weapons and she hear her out.

Back in Star City, Team Arrow, assisted by Felicity/Overwatch from the Arrow Cave, is chasing a very agile thief who has just stolen a piece of high tech gear. Speedy has him cornered on a roof top, but before she can unlease her arrow or act further she suddenly becomes woozy and faints. Luckily, the Green Arrow catches her before she falls off the building, however the thief gets away.

They take Thea to her apartment to rest, and Oliver is surpised to learn Thea is still struggling with her bloodlust and feels responsible. To which everyone responds, as they do seemingly every week, that this is not his fault. Malcolm, ever the concerned father is visitning and stresses that Thea give in to her urge to kill. He informs them that because Thea won’t indulge her bloodlust by hurting another, it will claim her own life.

Oliver is adamant that they do something, though he doesn’t think making Thea into a murderer is the right solution. When she shares that interacting with Dahrk briefly helped cure her, he arranges a meeting with him (through his wife, who is running for mayor now, UGH) to see about helping her. Thea isn’t willing to risk them owing Darhk a favor though. It is then that Malcolm and Oliver have a heart to heart, in which Malcolm delivers some surprisingly good advice. They need to let Thea make her own decisions. As much as they want to save her, this is her life and she needs to make the call. Ultimately, this leads to Oliver skipping the meeting due  her wishes and Thea in a coma.

Meanwhile, Oliver briefly snags a glimpse at the thief’s face and surprise– it’s Roy!  Everyone’s surprised and curious as to what he’d want with these seemingly random pieces of technology. Felicity puts it together that combined the stolen tech could create a tool that could essentially destroy the internet. However, it’s missing one crucial piece, which happens to be at Palmer Tech. Curtis just created a revolutionary power source.

Roy shows up to the company’s labs to take it, but Curtis puts up an impressive fight. Before he can get away, Team Arrow arrives, and acting on advice from Felicity, Oliver shoots him with an arrow. She spotted something in his eye. A contact like lens that worked as a camera. They remove it after making it appear he died, and Roy reveals the truth. He was out living his new life under a new identity when he received an email from an individual called the Calculator who threatened to expose his secrets and put Oliver at risk as well unless he did his biddings.

Felicity and the Calculator verbally spar using disguised voices over chat while she attempts to locate him. Though he blocks her out, he reveals his motives are even more sinister than they originally believed. He plans to use this web nuke to break water dams, mess with the subway system, shut down hospitals, etc., killing much of the city in the process.

Eventully, using one of Ray’s inventions, she infiltrates his systems and learns the location of his web bomb. The team goes to check it out and defeats his goons while they’re at it. The only way to stop the web nuke is to blow it up. Roy volunteers to stay behind and take care of it. He sees at his responsibility, and though it obviously pains Oliver he ultimately respects his decision. Roy escapes the blast though and the team experiences victory, at least temporarily.

Before leaving Star City again Roy finally gets a proper goodbye with ex Thea. The two acknowledge their love for each other and lament the fact that they can’t be together. She tells Roy that all she wishes is for him to have a normal life, get married, and have a couple kids. He tells her he wishes he could do that all with her, even though they both know that’s not possible fro him in Star City. It’s a bittersweet and teary reunion turned goodbye, but it was much needed.

Felicity, who had been struggling with confidence and capability issues at work following her accident, gives a excellent presentation of Palmer Tech’s new invention to the board members, after prompting by Curtis. In the audience: the Calculator. The big reveal: he’s Felicity’s father.

The episode concludes with Thea at the hospital, where a doctor tells Oliver her chances aren’t good. Oliver feels helpless and begs Thea not to leave him, only for an opportunity to save his sister to seemingly come out of thin air. Nyssa appears by Thea’s bedside and informs him the Lotus is able to reverse the effects of the Lazarus Pit and can save her. She has it and will freely give it on one condition: He kills Malcolm.