With all the mystery surrounding what might happen during these four final episodes, we now can see from the trailer that for the first part, Barry will sent back in time to the year 2000, where Thawne will be trying to kill kid Barry. It's quite a set-up, featuring a plethora of familiar faces from Barry's childhood, and quite a task for the Flash to try to deal with the reality of seeing his parents alive and well.  We're very curious to see how this will unfold, especially since we know Barry will still be missing for the second part of the finale. Check out the full trailer below:

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