Following Shazam! 2, THE FLASH is the next eagerly awaited installment from the DC cinematic universe. This project marks the first time the 'fastest man alive,' Barry Allen, embarks on his own journey, yet plays a role more crucial than anyone else.
Barry Allen's time-traveling adventure in THE FLASH will establish a completely new DC cinematic universe, albeit inspired by a legendary event in the comics.
Inspired by the legendary Flashpoint event

Drawing inspiration from the Flashpoint event, The Flash inadvertently 'rewrites' the timeline with numerous significant alterations. As revealed in the trailer, The Flash's mother was murdered when Barry was young, prompting his present self to return with the desire to save her. However, Barry's journey to the past has 'shattered the reality of the universe,' creating a new alternate timeline.

Essentially, there are 2 timelines in The Flash distinguished by a milestone: Barry's mother is deceased (the main timeline) and Barry's mother is alive (the alternate timeline). Both realities feature 2 versions of The Flash, yet there are also other intriguing characters appearing due to the multiverse chaos caused by the protagonist.
Supergirl's Role

According to DC's original Flashpoint event, The Flash's return and alteration of the past significantly impacted the Justice League. Among them, Superman's disappearance caused anguish for humanity. After crashing on Earth, the Kryptonian is apprehended and detained by the government, deprived of light.
This is likely to inspire the storyline of Supergirl in The Flash. In the trailer, Kara Zor-El is imprisoned, bearing a resemblance to Superman's plight in the original comics. Therefore, she may have been captured by the government, serving as an experiment in an alternate timeline after landing on Earth. Additionally, Kara is also a necessary component for The Flash's plan, being the 'metahuman' that the main character needs.
The Flash's Variant

When returning to the past to prevent his mother's murder, The Flash from the main timeline inadvertently encounters another version of himself. Both versions of Barry Allen are portrayed by Ezra Miller, yet they have different characteristics.
The presence of 2 versions of The Flash this time holds great significance as it solidifies the concept of the multiverse in the DC film. Together, both Barry Allens join forces to thwart the army of the villain Zod, as well as to find a way to restore the timeline to normalcy.

Additionally, a promo art of The Flash also surprisingly unveils a third version of The Flash, likely to be the hidden antagonist of the film (Reverse Flash or The Flash corrupted in the future of the Flashpoint timeline).
Keaton's Batman
Not only Superman but even Batman is heavily affected when The Flash returns to the past to save his mother. No longer the familiar orphaned billionaire Bruce Wayne portrayed by Ben Affleck, this Batman hails from a different universe, portrayed by Michael Keaton.

The appearance of Michael Keaton's Batman holds significant meaning as in the past, in Tim Burton's series of films, the fate of the Dark Knight remained uncertain. Thus, The Flash is considered the next chapter in Bat-Keaton's journey on screen, potentially even serving as the conclusion for both Bat-Keaton and Bat-Ben.
THE FLASH premieres on 16.06.2023 in 2D, IMAX, 4DX, ScreenX formats.