Ep 19. The Once and Future Flash

Barry Allen, aka The Flash, travels to the future in episode 19 of season 3, titled "The Once and Future Flash." He arrives in a city that is in utter chaos and despair. Barry has come to find out what happened to his friends and family after he disappeared in the present day six months earlier.

He discovers that everything in his absence has gone from bad to worse. Team Flash has split up and gone their separate ways. Central City is now ruled by a vicious villain named Savitar, whom Barry himself is responsible for creating. Savitar is unstoppable and has caused so much destruction that the city has been reduced to a post-apocalyptic wasteland. Barry is shocked and disheartened by the state of his once-beautiful city.

Barry's mission is to reunite the team and to save Iris West, his girlfriend and the love of his life, who has been targeted by Savitar as his next victim. To do this, Barry turns to his older self, who seems to have given up hope. Future Barry is older, grimmer, and hardened by years of fighting Savitar, and he has not seen his friends in years.

Together, the two Barry Allens begin their quest to save the city and those they love. They encounter old enemies and allies alike, but the older Barry's experiences have changed him. He is much different from the Barry that we know and love, and his cynicism creates tension between him and his younger self. They both struggle to come to terms with what they have lost and what they stand to lose.

As they continue their mission, the team starts to come together again. Cisco and Killer Frost work together to create a weapon that could kill Savitar, and Wally West, who has become Kid Flash, helps them battle the villain. In the midst of all this, Barry has to face his guilt and make amends for his mistakes.

The Once and Future Flash showcases Barry's vulnerability and desperation in the face of true hopelessness. This episode is a departure from the typical superhero storylines, delving into the psychology of one man's battle against himself and the catastrophes he has caused. The episode raises the stakes for the remainder of the season, and hints at possible tragedy awaiting Team Flash in the near future.