The CW has released an official trailer for "Crisis on Earth-X," next week's four-show crossover event between Supergirl, Arrow, The Flash, and DC's Legends of Tomorrow.

The first bit of the trailer focuses heavily on the wedding of Barry Allen and Iris West, but it is not long before it looks like a job for...well, about 20 superheroes, all of whom are in attendance when a group of armed storm troopers crash the ceremony, leaving the heroes incredulous and angry.

"I hate Nazis," Supergirl, The Flash, and Green Arrow seem to say in unison.

The crossover, which is more of a continuous "movie-like" experience than the somewhat more episodic "Invasion!" crossover from last year, centers on a group of invaders from Earth-X, a previously-unknown world in the multiverse where Nazis won World War II.

Along with the villains of that world -- doppelgangers of Harrison Wells, Oliver Queen, and Kara Zor-El, among others -- the audience will meet some of its heroes, most notably The Ray and Citizen Cold.

You can check out the trailer above.

"Crisis on Earth-X" is a four-hour event that will air on November 27 and 28 beginning at 8 p.m. and running for two hours each day; Supergirl (8 p.m. Monday), The Flash (8 p.m. Tuesday) and Legends of Tomorrow (9 p.m. Tuesday) will remain in their normal time slots but Arrow will move from Thursday to a 9 p.m. Monday placement for the week.