The CW’s Supergirl season three episode eight served as the first part of the four-way superhero crossover event featuring characters from The Flash, Legends of Tomorrow, Arrow, and Supergirl. “Crisis on Earth-X, Part 1” airing November 27, 2017 begins in a lighthearted manner with Legends, Arrow, and Supergirl teams RSVPing for Barry and Iris’ wedding.
Kara’s +1 turns out to be her sister, Alex (Chyler Leigh), after the devastating discovery that Mon-El is now married. The women gather for wine and manicures while Barry (Grant Gustin) and his Best Man/mentor Oliver Queen (Stephen Amell) try on their tuxedos. During the fitting, Barry admits he wants Oliver to follow suit and ask Felicity to marry him. Oliver’s not sure that’s a wise idea.
Meanwhile over at S.T.A.R. Labs, Harry (Tom Cavanagh) and Cisco (Carlos Valdes) have created a cure – with help from Caitlin (who they don’t credit) – for Firestorm that will return Jax (Franz Drameh) and Dr. Martin Stein (Victor Garber) to their normal selves. Neither will have superpowers so Firestorm will no longer exist. Jax looks upset at the possibility he’ll no longer be a member of the Legends.
The rehearsal dinner arrives and everyone mingles, letting their hair down and relaxing a bit. Alex hits it off with Sara Lance (Caity Lotz) and there’s some serious flirting going on. Martin tells Jax he’s come up with a formula that’s sort of Spider-Manish, but mostly not. All it will do will let him stick to things, without the webslinger’s other cool powers. But, at least it will allow him to return to the Legends team.
Elsewhere at the party, Kara (Melissa Benoist) tells Barry about Mon-El and how their relationship is over due to the fact Mon-El is married. Barry is sorry to hear about that, but he has a favor to ask of Kara that doesn’t involve donning a superhero suit.
Joe (Jesse L Martin) gives a toast, Sara and Alex make out, and Oliver takes Felicity (Emily Bett Rickards) aside to ask her to marry him. She loudly declines the proposal, declaring she doesn’t want to marry him.
The wedding day arrives and everyone looks terrific. Even Mick Rory (Dominic Purcell) is on his best behavior – or as close to it as possible. After learning her sister slept with Sara, Kara sings as the bride walks down the aisle. (Backing up a bit, there’s a weird scene with a waitress who seems to know Barry but he doesn’t recognize her. Fans believe she could possibly be Iris and Barry’s daughter from the future.)
The wedding’s interrupted by Nazis, causing all the heroes to express their hatred for white supremacists before shedding their civilian demeanor to switch into superhero mode. Fighting breaks out, The Flash stops bullets from striking his friends and wedding guests, and Harry tries to clear the room. Arrow, Supergirl, and the Legends teams spring into action. Alex and Sara prove to be a killer duo as they beat up Nazis while Supergirl takes on an evil version of herself as Arrow fights his own evil doppelganger. Killer Frost (Danielle Panabaker) is called into the action, as is Vibe.
Our heroes win – for now – and Kid Flash (Keiynan Lonsdale) is charged with taking Joe (Jesse L Martin) to safety. Mick wipes the memories of all the non-superhero guests. Cisco’s hurt and is out of commission for a while, and they all realize this fight isn’t over yet. However, they have captured one Nazi.
They discuss the purpose of the attack and decide it was to kill all of Earth’s heroes in order to “Make Earth Aryan Again.” They reiterate how much they hate Nazis.