Plot Summary[]
After Barry questions Eobard about his motives, Barry and the gang discuss about the time travel and the effects. Barry goes out to see advice of his father who advises Barry to not disrupt the natural order as it might change Barry. Using Eobard's proposal of having Barry going fast in the particle accelerator with another particle going opposite direction, Professor Martin states it's a valid plan. Cisco doesn't want to put Barry to risk. Ronnie helps Cisco with the plans in making a time machine. Eobard applauds Ronnie for finding another replacement for the Tungsten which generates flammable dust which causes temporal shearing. Eobard suggests they use Cobalt Resin. Then, Cisco shares with Eobard of what said to Cisco in alternative timeline, that Eobard called Cisco a son before killing him. Eobard concludes that Cisco was affected by the particle accelerator and that Cisco had gifts of seeing these things. he tells Cisco that this gift was given by him out of love.
While Joe and Barry have an emotional conversation about their lives on the line, Eddie and Iris talk about their future together. Afterwards, Ronnie and Caitlin have their wedding with Martin Stein acting as their Rabi.
On the day of the mission, Barry runs as fast in the particle accelerator. Eobard shares how Barry is seeing the Speed Force where he can see all the timelines. As soon as Barry hits the right amount of speed, Stein has his group inject the hydrogen particle. Barry enters the time stream and arrives on that fateful night. The future Barry signals to Barry to not intervene. Barry closes the door and painfully listens to his mother being stabbed. After Future Barry rescues the past Barry, Barry enters the room to listen to his mother's last words.
As Eobard gets into the time machine, a helmet is spit from a wormhole. Suddenly, Barry smashes the time machine. Eobard gets angry that Barry didn't save his mom and get the life he wanted. Stein instructs everyone to shut the wormhole's generator. Eobard grabs and pins Flash. Before he could kill Barry, Eddie shoots himself. Cisco explains if Eddie dies, Eobard is being erased from existence due to being Eddie's descendant. Iris rushes to Eddie's side. Eddie shares his last words that he is a hero.
Once Eobard dies, a wormhole reopens. Outside, Martin explains the singularity is eating everything. He states the only way to stop the singularity is to disrupt its motion. Barry runs up to the singularity and runs as fast as he can.