The Flash Season 3 B
The Flash season 3 B is everything post Flashpoint. This will deal with a whole new storyline and explore the aftermath of Flashpoint.
Flashpoint Changes
Barry Allen returns to a world that is different. It is not like the normal world. For starters, Cisco Ramon's brother died in a car accident. This has led to Cisco not being the happy comic relief. He will become that character again but right now, he wants to become a vigilante and fight crime as Vibe.
Iris West and Joe don't have the same relationship as before Flashpoint. There are more problems now as Iris knows Joe threw her mother out. Because of more reasons than her being a drug addict. This has fueled Iris's hatred towards her father, something they will deal with later on.
Wally West's life is very different. In the new timeline, he grew up with Joe and Iris. But Joe isn't his real father. Daniel West is. Daniel is Joe's brother and we will learn that Iris's mother cheated on Joe with Daniel. Which led to Wally being born. But Joe told Wally he was his father to make sure Wally would get a normal childhood.
Another change caused by Flashpoint is that Caitlin Snow now has powers. She has cold powers which only start to manifest now. These will be a large part of the season as Caitlin will get some character development through it.
Plot
Barry Allen gets to the "normal" world where he meets Joe and Wally. He learns of Iris and Joe's relationship. We get some exposition to learn everything about Iris and Joe, also how Cisco is now. We will then have a scene where Barry confronts Joe about Daniel. Joe explains Daniel was a criminal and he wouldn't be a good father to Wally. Barry believes Wally should know but says Joe needs to be the one to tell him.
We are later introduced to Doctor Alchemy. Alchemy has a connection to Flashpoint and is able to give people the same meta-humans powers they had in Flashpoint. Which will be the way we get new meta-humans.
We will also introduce Julian Albert who is a rival to Barry as a CSI through the season.
Team Flash soon learns of Doctor Alchemy and decides to stop him. At first, Barry goes alone but Alchemy tries to use Wally to get to Barry. He will hear a voice in his head before he gains his super speed. When Wally gets powers, he wants to become a hero like Barry. Until Doctor Alchemy reveals to Wally who his father really is. Leading to Wally leaving Team Flash.
After this, Wally will be somewhat of a villain for an episode. Barry will be after him but when he and Joe realize they can't reach Wally, Joe goes to speak to Daniel. Explaining to Daniel that Wally is his son and he needs his help. It all leads to Daniel talking to Wally and convincing him what Joe did was right. Joe also reveals why he threw Iris's mother away and the two start to bond again.
Doctor Alchemy continues to create meta-humans. Even trying to recruit Caitlin Snow. Telling her that Caitlin will never be accepted. Everyone will always fear that she becomes her Earth 2 counterpart. This leads to Caitlin talking to her mother about her powers. During this, she uncovers the truth. Caitlin's mother killer Caitlin's father. This makes Caitlin go on a rampage as she tries to kill her mother. The Flash and Wally get there and stops Caitlin. Which leads to her feeling betrayed. Caitlin's mother then tells Caitlin she didn't kill her father. Her father had the same powers as her and gave them to Caitlin as well because he went mad. It led to Caitlin's mother locking her father in a facility in the Artics. Caitlin is still able to get away.
We get to see more of Barry actually training Wally. Wally will learn a lot of abilities we've seen Barry use in season 1. He will also help Wally learn from Barry's mistake from season 1. But Barry will have a hard time as it is the first time for him to train someone.
Later down the line, Barry beats Doctor Alchemy and unmasks him. Revealing Julian Albert. We also learn Julian has been mind-controlled by Gorilla Grodd. Grodd has been behind everything all along.