**This article will contain spoilers! Read at your own discretion. Footnotes have additional information**

     Four shows, four episodes, four hours. That is the most exciting combination when it comes to seeing your four favorite shows doing the biggest crossover in The CW’s history. The highly known DC shows, which include Supergirl, The Flash, Arrow, and Legends of Tomorrow, combined to make one of the best and most memorable TV crossovers ever. The most exciting thing about this crossover is that it was filmed like a movie. Yes, it was broken up between four shows, but none of the episodes focus on that specific show.

     The long awaited crossover brought a whole new demographic of viewers, some who only watch one or two of the shows, who got the chance to see what the other shows are like. This has pulled more viewers toward each of the four shows. The four-part crossover split up the four shows into two nights of TV, and yes, that means a major cliffhanger from Monday night. The story behind the crossover is simple, yet super complicated (pun intended).

     The first episode (Part 1) is the new Supergirl episode, and Barry and Iris are getting married! All the superheroes show up to support them, and Barry asks Kara to use her “non-superpower ability” that he found out she has in the last Supergirl/The Flash** crossover, which is that she can sing. The Flash wedding begins, Kara sings “Running Home to You” as Iris walks down the aisle, Barry and Iris do their vows, and everything is going perfectly until suddenly Nazis completely obliterate the wedding. Big fights take place as the church is destroyed and there are villains fight the heroes until Kara does a ‘thunderclap’ move, sending Overgirl into the wall, and Dark Arrow tells his people to fall back as they quickly escape the church.

     Part 2, which takes place during the new Arrow episode, brings about the newfound information of Earth-53*, which is news the heroes take as a major surprise. The biggest surprise, though, is when we learn that there is a version of the heroes on all of the other Earths. This tells us that these Earth-X characters are just the alternate and evil Earth copies of Kara, Oliver, and Barry. Overgirl is Kara-X, Dark Arrow is Oliver-X, and Jax is Reverse Flash. Episode two is where all the crisis starts to begin, and it sets the storyline in motion, which makes the viewer want to binge watch all four episodes.

     Part 3, The Flash, & part 4, Legends of Tomorrow, are the most intriguing and exciting of the crossover; so, to figure out what happens, you will just have to watch them. The “Crisis on Earth-X” made TV crossover history, and it is definitely worth the four hours of watching.

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     *In DC theory there are 52 Earths. Kara Zor-El (a.k.a. Kara Danvers) and Alex Danvers are on Earth-38, Barry Allen and his team are on Earth-1, and the others’ home Earths are unknown. Earth-X is explained to be Earth-53, and it is the world where Hitler won World War 2, therefore making it a war centred planet. “There’s a 53rd earth, and it’s called Earth-X. It doesn’t have a designation because it’s a place so awful, so horrific, no sane person would ever travel there. It’s basically our earth–same history, same timeline– with one crucial and critical difference. The Nazis won the war, and New York, London, Paris, Moscow–all obliterated.”

     **Supergirl and The Flash have done 5 (including Crisis on Earth-X) total crossovers. In order, Supergirl season 1, episode 18 “World’s Finest”, The Flash season 3, episode 8 “Invasion”, season 3, episode 11 “Dead or Alive”, season 3, episode 17 “Duet”