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"Oh, why should the spirit of mortal be proud? Like a fast-flittering meteor, a fast-flying cloud, a flash of the lightning, a break of the wave, he passes from life to his rest in the grave."
Joan Williams quoting William Knox

"A Flash of the Lightning" is the second episode of the sixth season of The Flash, and the one-hundred-sixteenth episode overall. It aired on October 15, 2019. This episode is also the second in a subset of the sixth season episodes the writers dubbed as "Blood and Truth."



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Starting where we last left off from "Into the Void", Barry and Iris have a conversation about what just happened, and Iris convinces Barry that what crap The Monitor said and schemes to change the timeline. Barry gets the idea to travel to the day after he vanishes.

Later, Barry travels to the future but is blocked by a wall of Anti-Matter and is sent out of the Speed Force timestream, slightly injured: he gets help by Iris; and Gideon suggests Barry go to meet up with Jay Garrick on Earth-3.

Cecile, Joe and Criminal Allegra Garcia are in a room talking about Allegra's current situation, and Cecile lets Allegra go free on a condition of wearing Meta Cuffs.

On arrival, Jay helps heal Barry and agrees with Barry's decision to Time Travel. Jay's Wife Joan Williams, who looks like Barry's mother. Barry and Jay work together and sends Barry's mind through the barrier, he sees billions of future's and timelines. He sees one where Central City (Earth-1) is consumed by the anti-matter and that he must die to save everyone, proving The Monitor right.

Back on Earth-1, Ralph and Iris find Allegra with a dead body and assume she is the one who did it. Joe later arrests her sending her back to CCPD where Cecile rushes in and bargons with her, and Allegra reveals that it wasn't her, and Ultraviolet - her sister. Who was meant to be "dead".

Barry returns to Earth-1 and talks to Joe, and later faces Esperanza and stops her.

Later, Barry vows to prepare Team Flash for Crisis.



Guest starring[]




  • The episode's title is a reference to a line from the William Knox poem "Mortality", which Joan Williams reads to bring Barry back to consciousness.
  • Jay tells Barry that he had spent a year tracking the spread of antimatter throughout the multiverse, showcasing a map of the Earths he had discovered thus far. The map featured annotations from Jay, which ranged from the Earths that have the best vegan food and tequila, to which superheroes call which Earth home. Towards the top of the list, next to Earth-51 (his home Earth in the comics), is the name "Thaddeus Brown." Both Thaddeus and Earth-51 were previously mentioned in "Gone Rogue". In the comics, Thaddeus was the first to hold the mantle of Mister Miracle.
    • Also on his map, Jay predicts that the antimatter wave would next appear on Earth-2. This was seen in the Arrow episode "Starling City", which aired directly after this one.
  • In the recovery bed, Barry tells Joan that she should have used Lady Gaga to reawaken him. This is a reference to "Pilot", where Caitlin and Cisco played a Lady Gaga song when Barry woke up from his coma.
    • It was also used again before in "The Flash Reborn" when the team needed to awaken Barry after he was brought into S.T.A.R Labs after his time in the Speed Force.
  • The man who saved Esperanza was wearing the logo of the Black Hole organization, which in the comics was connected to Godspeed.
  • Barry's vision shows Cisco suited up in his Vibe suit again, suggesting that he'll somehow regain his powers. His powers are later indeed restored by Mar Novu in "Crisis on Infinite Earths: Part Three".
  • Central City in antimatter

    A possible future of Central City (Earth-1) consumed in antimatter.

    Of all the futures Barry saw, he did not see the true future. (I.E. Iris, Killer Frost, Vibe and Elongated Man were not in Central City (Earth-1) when the anti-matter consumed it, or Barry's death to stop the anti-matter wall.)
  • Cisco calls Killer Frost a White Walker, referencing Game of Thrones.
  • Barry wears the same clothing he wore in "What's Past is Prologue" when he time traveled.
  • Cisco asks Killer Frost, "what did you do with your Tuesday?" a breaking the fourth wall joke as the show airs on Tuesday.
  • Gideon suggests Barry's top speed is 1/80 that of the speed of light, or about 2325 miles per second.
  • This episode features the debut of Kayla Compton as Allegra Garcia who would later become a series regular in Season 7.

Behind the Scenes[]

  • Despite Barry only seeing a victory against the Crisis needing him to die, the fact there was more episodes for Flash's Post-Crisis era proved that he would survive. Not to mention that the Barry Allen of Earth-90 was confirmed to appear during the Crisis on Infinite Earths event. These two facts unfortunately made it quite easy for fans to figure out the surprise the writers planned.
  • After the episode's premiere, The Flash Twitter account tweeted a Behind the Scenes still that never made it into the final airing that of Iris making it to S.T.A.R Labs as Barry recovers after his encounter with Ultraviolet at CCPD.
    • When the Season was released on DVD and Blu-ray, the deleted segment was not featured therefore rendering the scene lost.