Sunday's Supergirl episode launched the Arrowverse's five-part “Crisis on Infinite Earths” crossover - at it began with a major character' death, as well as the deaths of entire universes.
Spoilers ahead for the December 8 episode of Supergirl.
The episode opens up with the Monitor monologuing about the end of the multiverse with key moments from Arrow, The Flash, Supergirl, Batwoman, DC's Legends of Tomorrow, and previous crossovers.
The Crisis begins with the destruction of some classic and current DC realities.
- The Burton-verse is destroyed as the 1989 Batman's Robert Wuhl (reprising his role as reporter Alexander Knox) is shown holding a newspaper emblazoned with the headline "Batman Captures Joker."
- DC Universe's Titans is shown destroyed with a short scene with Hawk (Alan Ritchson) and Jason Todd (Curran Walters).
- Earth-X, from the Arrowverse crossover of the same name, is destroyed.
- the 1960s Batman TV series timeline is gone, but not before a cameo by Burt Ward as Dick Grayson/Robin, walking Ace the Bat Hound.
The next Earth on the docket is Earth-38, Supergirl’s home. Star Trek: The Next Generation’s Wil Wheaton makes a cameo appearance with an “End is Nigh” sign, seemingly a homage to Watchmen and Superman II.
The Supergirl team rallies the troops when they find out about the universe’s impending doom. Kara discovers that Argo City is in immediate danger - and that's where where Clark Kent, Lois Lane, their newborn son, and her mother currently reside. History repeats itself with only moments of this Earth to spare, as Lois and Clark send their son off to safety in a pod - homaging Superman's own origin. - as Argo City is engulfed into the dangers of this Crisis.
Arrow’s Lyla Michaels takes on the role of Harbinger as she transports Kate Kane, Oliver Queen, Mia Smoak, Barry Allen, Ray Palmer, and Sara Lance to Supergirl’s Earth in the final moments of this universe. It’s revealed that Lyla was able to save Clark and Lois before Argo City was destroyed, but could not save Kara’s mother. Their mission is to help protect the Quantum Tower from the Anti-Monitor and his shadow demons who want to destroy it. If they protect the tower, they can save Supergirl’s Earth, according to Lyla.
As the superheroes are put into motion, Superman and Supergirl have a heart-to-heart. Superman blames himself for not being able to stop this destruction because he took time to spend with his family. Kara is able to relate to his anxieties, but reminds him of the hope they both share because of Krypton.
As all this is going on, Oliver Queen prepares for what he was told by the Monitor - that he would die during this Crisis. Stephen Amell's character passes down the Green Arrow mantle to Mia Smoke with her own suit. Arrow then meets up with the Flash, where Barry opens up about the “Crisis” headline that predicts Barry’s death. This gets Oliver upset, and he calls the Monitor. Oliver made a deal with him that if he traded his life then Kara and Barry would be safe - which if this headline is true, would break that deal.
The Supergirl team continues to prepare for the end of the world. Alex Danvers recruits Lena Luthor to help save the world, but is reminded of their rocky relationship as Lena still hasn’t forgiven Alex, Kara, and the rest of Team Supergirl for lying to her about Kara’s secret identity. Although, she is willing to put this to the side to help save the people of their Earth.
Sara, Brainy, and Lois go on their own side mission to Star City 2042, a version of this has been previously seen on DC's Legends of Tomorrow as a dystopian world. They find Jon and an older, even more jaded Oliver Queen. Oliver is surprised to see Sara alive, and still blames himself for her “death” on the Gambit. Sara reassures Oliver that their trip on the Gambit was for the best. They wouldn’t be the heroes they are today without it.
The other heroes of Team Supergirl (Martian Manhunter, Kelly Olsen with Guardian’s shield, and Dreamer) are helping the citizens of National City to be safely portaled away, with the help of Lena and Alex dealing with the science aspect of this feat.
The rest of the heroes are fighting off the shadow demons as they stall for more time as the Supergirl team continues to transport people to Earth-1. The Monitor tells the heroes that there isn’t any more time for this Earth and begins to transport the heroes away, but Oliver isn’t ready. He wants to save everyone, and with no arrows left he fights to his last breath. Oliver is brought to the other heroes on Earth-1 as he gives his final words to his loved ones.
The Monitor reveals that this wasn’t the time Oliver was supposed to die in Crisis. Things are turning out differently than expected. Nash Wells, now calling himself 'Pariah,' also shows up and tells the group that he released the Anti-Monitor, and now is living his penance for his mistakes.
"Crisis on Infinite Earths" continues with Monday's Batwoman episode airing at 8 p.m. Eastern on the CW.