The latest updates and spoilers for "The Flash" Season 4 reveal the plot synopsis for the show's midseason finale and it involves Killer Frost and Amunet Black a.k.a. Blacksmith. [VIDEO] The two metahumans had a history together before the events of the fourth season and it seems that their paths will cross again but this time they are working together.

Cast member Grant Gustin talks about Barry Allen and Iris West's wedding during the "Crisis on Earth X" crossover and how their marriage is featured on a different show.

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Midseason finale plot

According to The Hollywood Reporter, "The Flash's" midseason finale will air on December 5 and the plot details revealed that Caitlin Snow has been kidnapped by Amunet Black using the metahuman handcuffs to prevent her from using her ice powers.

Caithlin is forced to work with Amunet by performing a tricky medical procedure and if she fails, the latter will kill her.

The midseason finale synopsis also revealed that Barry Allen is caught in a speedster-proof trap created by the show's main antagonist, Clifford DeVoe a.k.a. The Thinker. Team Flash will have a hard time figuring out a plan to save both Barry and Caitlin from their metahuman archnemesis.

Clifford has been manipulating the events of the fourth season ever since Barry returned from the Speed Force. He tries to capture the 12 metahumans that were affected by the dark matter from the wormhole and he has been three steps ahead of Barry and his team.

Wedding Jitters

"The Flash" TV series star Grant Gustin shared his thoughts about his character walking down the aisle with Iris during their wedding day as he told Screenrant that they had to prepare for this day to come ever since the third season, and this important event will happen in a different show.

"We've been leading up to this wedding for a long time and I think it's kind of in some ways fitting that it's part of the crossover because it's also a little strange that we've been leading up this wedding it's not event on The Flash; it's technically on a different show," Gustin said. "So I'm interested to see how viewers feel about that, but it's also how it goes."

Barry and Iris's wedding will be interrupted by the invasion of the evil Earth X army led by Overgirl, Prometheus X, and Oliver Queen's doppelganger. Harrison "Harry" Wells revealed to the DC TV heroes that Earth X is the 53rd world in the multiverse and it is being ruled with an iron hand.

The heroes will work together with The Ray and his Freedom Fighters to stop their evil counterparts and prevent them from using a doomsday device in their world.