The episode starts with the night the particle accelerator exploded and created so many metahumans. It is a football game and Jefferson “Jax” Jackson’s team won due to his skill as a quarterback. Then the shockwave from the explosion hits, after Jax has been able to get most of the people at the games clear. He seems to be affected by the shockwave. In the present, Professor Stein is in shock, but Cisco is able to come up with a temporary manner to stabilize him. The team has come to the conclusion that they need someone able to merge with Professor Stein in order to stabilize him. Without Ronnie Raymond, he is falling apart on a molecular level. The team has two possible candidates, Jax, a mechanic and former football player, and Henry Hewitt, a scientist. It is clear Caitlin favors Hewitt over Jax based on her personal preferences. Barry covertly gets the blood samples to test both candidates.
Iris and Joe are mulling over their past and the re-mergence of Francine West in their lives. At the Precinct, Patty brings some shark teeth for Barry to test. There have been sightings of a humanoid shark creature. According to the blood tests, Jax is the better match, but Caitlin favors Hewitt due to his education and vocation. They decide to meet both candidates. Jax is not into the idea at all. The shockwave cost him a possible football career and college education. Iris’ meeting with Francine does not go well; she is distrustful of her mother. Caitlin brings Hewitt to S.T.A.R. labs and clues him into to what is going on without consulting anyone else. Hewitt is genuinely excited at the prospect of merging with Stein. The merge with Hewitt fails, and Hewitt rages. He also seems to blame Caitlin for getting his hopes up. It looks like even though the merger did not work, Hewitt it seems was affected by the attempt.
It seems that Harrison Wells steals an item from Mercury labs and is seen by Dr. McGee. Joe and Patty investigate. Joe asks Patty not to reveal who the suspect is to Barry. Francine informs Joe she is dying. The team tries to convince Jax to merge with Stein, but Caitlin’s attitude and Jax’s own attitude result in Jax refusing to merge. Hewitt loses his cool with a superior at his job and his powers begin to lash out. Caitlin apologizes to Jax. As she does this, Hewitt shows up and attacks her and Jax. Jax and Caitlin head to S.T.A.R. labs. There Stein and Jax successfully merge. Hewitt attacks folks at Jax’s old high school football field. Together Firestorm, the Flash, and the team defeat Hewitt when they realize that Hewitt is like a controlled fusion device, a tokomak. That is the more powerful he gets the more unstable he is.
Iris confronts her mother as being not completely truthful to Joe and her. She informs her mother that as a journalist she is skilled at digging up dirt and discovers she has a possible brother. She tells her mother that it would hurt her father to know he had a son that he had no chance is helping raise. Stein and Jax go to Pittsburgh, PA to get help to learn their abilities better. Barry confronts the shark creature. It tells Barry, Zoom sent him to kill Barry. Patty attempts to help, but shooting the creature does not help. A mysterious person incapacitates the creature then runs off. The mysterious figure is Harrison Wells.
Easter egg time, Jefferson “Jax” Jackson is a new character, but he seems to be an amalgamation of the comics version of Ronnie Raymond and Jason Rusch, a later part of the Firestorm matrix. In the comics Ronnie is a jock, as opposed to the scientist and engineer he is in the Flash TV show. Jason is an African-American science nerd. They merged Ronnie’s being an athlete with Jason’s ethnic background for Jax. In the comics Jason has merged with both Prof. Stein and Ronnie. Henry Hewitt is the Firestorm villain, Tokomak. That is the reason for the line about the controlled fusion device. In the comics he is Caucasian and the owner of an energy corporation.
DC has multiple humanoid shark creature villains. The top three are the Shark, Carcharo, and King Shark. The Shark is a Green Lantern villain. He was a shark near a nuclear testing area in the Pacific Ocean that became humanoid due to the radiation. Carcharo is a mutant human with shark features; he was a villain of the super team Infinity, Inc. Infinity, Inc. was originally from Earth Two. King Shark was the product of the God of all Sharks and a human woman. He was a serial killer in Hawaii and a Superboy villain. Based on the introduction to Earth Two and Zoom being involved, I think it is Carcharo.
Iris’ brother is more than likely Walter “Wally” West. The character has been cast, so this is not a shot in the dark. In the comics, Wally is Iris’ nephew, former Flash sidekick Kid Flash, and the third person to become the Flash. He was the more wise-cracking Flash than Barry. He was also Barry’s successor as the Flash.
They packed great deal into this episode. They continued to ratchet up the intensity for the Zoom storyline and anticipation for DC’s Legends of Tomorrow. Jax and Prof. Stein are slated to members of the team on Legends of Tomorrow. The hinting of Wally West was exciting too. The Flash and Arrow are paying homage to the DC Comics characters, but not sticking rigorously to comics’ continuity. The episode showed that preconceived notions do not always fit reality. This was a hard lesion Caitlin learned. Iris presented the idea that it is smart to trust, but verify. Barry showed that there is more than one path to being a hero. Overall I give this a B+.