Ep 1. The Flash Reborn

As the fourth season of The Flash begins, we find Barry Allen trapped in the Speed Force - a prison of his own making, where he has been stuck since the end of season three. His friends and family are struggling to cope with his absence, and it seems that the city of Central City is worse off without its protector. But things are about to change.

The episode opens with a strange occurrence in Central City - people are disappearing out of thin air, seemingly at random. The only clue to what is happening is the appearance of a strange energy that seems to be causing these disappearances. As the team at S.T.A.R. Labs investigates, they come to a shocking conclusion: the energy is actually the remnants of the Speed Force, and somehow it has been released into the world.

As they try to figure out what this means, they receive a visit from an unexpected source: Wally West, a.k.a. Kid Flash. Wally has been filling in as Central City's protector in Barry's absence, but he is starting to feel the strain of trying to live up to his mentor's legacy. Still, he is eager to help and offers his assistance in any way he can.

Meanwhile, Barry is still trapped in the Speed Force, but he is not alone. He has a strange vision of his old friend and mentor, Ronnie Raymond, who appears to him and tells him that he needs to escape the Speed Force in order to save the city. With Ronnie's help, Barry begins to realize that he can use his connection to the Speed Force to break out of his prison.

Back in Central City, the team at S.T.A.R. Labs is struggling to contain the energy released by the Speed Force. They realize that they need to find a way to harness the energy and use it to bring Barry back. With the help of Cisco, they create a device that will allow them to channel the energy into a bolt of lightning, which they hope will bring Barry back safely.

As the team prepares to use the device, they are interrupted by a new villain who has appeared in Central City - a powerful meta-human who seems to have control over dark matter. This villain, known as "The Thinker," is unlike any opponent they have faced before, and it quickly becomes clear that he poses a serious threat to both the city and the team.

With the threat of The Thinker looming, the team must race against time to bring Barry back and find a way to stop this new villain. The lightning bolt is fired, and it seems that they have succeeded in bringing Barry back - but what they don't realize is that something has gone wrong with the process. As Barry emerges from the energy, he seems... different.

As the episode ends, we are left with a lot of questions. What has happened to Barry? How will he cope with his time in the Speed Force? And what is the true nature of The Thinker's plan? The Flash Reborn sets up an intriguing new season for The Flash, with plenty of twists and turns to keep fans guessing.