Worried that Prometheus's accusations of hum being nothing but a common killer might be true, Oliver finds a single ray of hope in the apparent resurrection of Laurel Lance. Felicity is not so optimistic, being out for blood in the wake of the murder of her boyfriend, Billy Malone and skeptical of any apparent miracles in the face of her own loss. Meanwhile Diggle must face a new threat to his life and Curtis has a crisis of faith regarding his status as Mister Terrific.
The Green Arrow comics of Judd Winick (storyline with a doppelganger trying to throw Team Arrow into chaos) and The Princess Bride (Prometheus, a man in black, has built up an immunity to the drug Green Arrow tries using on him.)
Ignoring the issues with getting past the security in STAR Labs in the first place (it's practically a running gag on The Flash how easily people are able to get into the building), just how the heck did Prometheus find out that Black Siren existed in the first place?
With all the secret information Prometheus was able to gather in order to make Black Siren pose as Laurel (i.e. The Legends, The Waverider, etc.) he somehow overlooked details like her being a recovering alcoholic? (Her being fired for drug abuse back in Season 2 was a matter of public record and she attended AA meetings.)
Why doesn't Prometheus just kill Black Siren after she exposes herself when his whole master-plan is based around making Oliver suffer? The murderous metahuman is nothing but a liability at that point - not that making use of her made much sense to begin with.
Oliver talks about how Black Siren lost her family, yet no mention of this was made in the episode. (A deleted scene?)
Emily Bett Rickards is the episode MVP. She gets some nice non-verbal acting in, with Felicity's subtle reactions to recovering alcoholic Laurel not blinking at being served booze at the party. She also gets a chance to show the steely side of Felicity that we see so rarely, when she confronts Black Siren on her con-game.
Rick Gonzales runs a close second, however, showing more development as Rene Ramirez, ironically enough, playing opposite Echo Kellum as Curtis Holt has his first big breakthrough in turning Mister Terrific into a technology-focused hero rather than a physical combatant. We see the wise side of Wild Dog here and it is a welcome thing after so many episodes where he was the generic hot-tempered teammate.
The twisted music used during the fight between Green Arrow and Prometheus is rather nice.
Felicity makes a reference to her Q-mail account. In the New 52 DC Comics Universe, Queen Industries was an Apple-style technologies firm which sold Q-phones.
Rory compares Prometheus to a dybbuk. In Hebrew mythology, a dybbuk is a vengeful spirit capable of possessing others. They are believed to be the dislocated souls of dead people.
Wild Dog refers to Black Siren as "Trinity". This is a reference to the heroine of The Matrix Trilogy, who also wore a lot of black leather and long-coats.
The Bratva boss who tortures Oliver is named Ishmael Gregor. In the original DC Comics, Ishamel Gregor was a Russian gangster who took on the identity of the demonic supervillain Sabbac.
In the flashback, Oliver is saved from the corrupt Bratva by a woman who introduces herself as Talia. This is Talia Al Ghul - daughter of Ra's Al Ghul, in the comics, where she was a love interest of Bruce Wayne, occasional leader of the League of Assassins and the mother of Damian Wayne. She does not give her surname during the brief appearance we see here but we did see her as a young girl in L109.
There is a technical difference between an alternate reality and a parallel universe, according to Curtis.
Felicity laces Black Siren's water with tracking nanites - the same ones in Oliver's tracking arrow, which he used to follow Malcolm Merlyn in 304 and used to follow Anarky to Damien Darhk in 410.
Black Siren's cry works on a more powerful frequency than Black Canary's mechanical cry.
Curtis tries to build a portable power dampener to use against Black Siren.
The dart Green Arrow uses on Prometheus is treated with Diazepam - a drug used for treating anxiety disorders and muscle-spasms. The drug can be used as a mild sedative.
Rory: I guess spontaneous resurrection is as good as any reason for a party....
Felicity: ... but?
Rory: But, we haven't even buried Detective Malone yet.
Felicity: It feels weird to be celebrating?
Rory: It doesn't feel weird to you?!
Felicity: Yes- Weird. Yeah. Weird or... I guess.... after the past four years, it's just hard for me to accept good news.
Rene: Weird, man! She was dead. Now she's not.
Oliver: That's time travel for you.
Rene: Well, I don't mean Laurel being back is what's weird. It's how you're all reacting to it, like it's happened before.
(Oliver just stares at Rene mutely.)
Rene: It's happened before?!
Oliver: (sighs) The Lance sisters have a habit of coming back to life.
Rene: ... wait, what?!
(Felicity explains that the party for Laurel was just a ruse to get a DNA sample.)
Rory: You know, there's looking a gift horse in the mouth, and then there's-
Felicity: - being driven by paranoid delusions, drawing comparisons on genetic base pairs? Yes, I'm aware. Thank you.
Oliver: Someone once told me that a circumstance could make something poison or nectar. What they meant was that we get to choose what we are. We get to choose who we are. So tell me... who are you?
Felicity: Oliver seems to think that because you look like Laurel that you can become her.
Black Siren: And what do you think?
Felicity: I think...you should get used to living in cages. There's a part of him that blames himself for Laurel's death. It's who he is. So when he looks at you, he doesn't just see Laurel. He sees a shot at redemption.
Black Siren: Wow. It must be really frustrating... that he doesn't listen to you.
Felicity: Oh, I'm used to it.
(Curtis describes his idea of building a portable power dampener to fight Black Siren.)
Rene: That's awesome!
Curtis: Yeah, well - ideas are one thing. Executing them is another.
Rene: You don't get it, do you?
Curtis: Get what?
Rene: That maybe instead of beating yourself up about what you can't do, take a moment and appreciate what you can do. Because it's pretty bad ass.
(As Black Siren's powers fail, she turns to see Mister Terrific holding up a small radial dish.)
Mister Terrific: You really need to shut your damn mouth!
(Two bikers play pool in a biker bar. A waitress walks up. A woman is sitting at the bar behind them.)
Waitress: You boys want another round?
Biker 1: No, I was thinking of ordering something that's ah... not on the menu, huh?
(The first biker steps in close and tries stroking the waitress' hair. She turns around and runs into the second biker. The two close around her.)
Biker 2: Hey, where you going, baby?
Woman: Seriously, could you two be any more of a cliche?
Biker 2: Oh, don't worry, sweetheart. There's plenty of me to go around.
Woman: (still looking behind the bar, not turning to face them.) I thought people like you only existed in the movies. You know? Two guys trying to overcompensate for their lack of manhood by taking it out on a defenseless woman?
Biker 1: What are you gonna do about it?
(Close-up on the woman's face. She smiles a close-lipped smile.)
(Cut to outside the bar. The glass windows suddenly explode outward, as a piercing cry is heard and the two bikers are thrown out through the windows. The woman steps forward to inspect her handiwork.)
"Laurel" claims that she was teleported onto The Waverider by Sara Lance as she was dying and the advanced technology there was used to heal the embolism that killed her in 418. She then asked to be brought back to Ollie's present.
Rory says he doesn't sleep much - or at all - ever since he became Ragman.
"Laurel" turns out to be Black Siren - the Laurel Lance of Earth Two - last seen in F222.
The statue of Black Canary is destroyed during the fight with Black Siren.
Prometheus has built up a tolerance for Diazepam.
Black Siren is transferred into a secure ARGUS lock-up.
In the flashbacks, Oliver is saved by Talia Al Ghul.
The final scene shows an unnamed woman, who easily defeats two bikers showing unwanted attention to a biker bar waitress with a sonic cry.
Cisco Ramon apparently told Felicity about the battle with Black Siren in F222.and how she was being held in STAR Labs' pipeline at some point in the past.
The Fridge Factor
Black Siren is still an incompetent villain any way you slice it.
The Winick Factor
Pretty much the entire team has to be nerfed and Ollie's characteristic paranoid put aside for an episode in order for Black Siren to be any kind of threat.
The Bottom Line
A mixed bag. Even with a script that seems to have been written to her strengths as an actress, Katie Cassidy still overplays her part as Black Siren, once again coming off as a parody of Killer Frost. Despite this - and Prometheus' plan to utilize Black Siren not making a bit of sense even ignoring how the heck he found out about her in the first place (which the show does) - there's a lot here that works, despite the weakness of the script. Putting Curtis on the path to becoming the tech-based hero that Mister Terrific is in the comics is a good start and the scenes with him and Wild Dog do a lot to develop his character as well. Stephen Amell manages to sell Ollie's uncharacteristic optimism here and Emily Bett Rickards is on fire playing the more cunning and proactive Felicity. And after an entire episode devoted to showing everything Black Canary isn't, the final minute of the episode shows us everything Black Canary should be.