As the police investigate the murder of one of the city's crime families, Barry suspects that the killer may be a metahuman who can control poison gases. As Barry and Joe work to discover the killer's identity, Wells and his team work to retrofit the particle accelerator into a prison for metahumans where they can begin to find a way of reversing their mutations. This brings up difficult feelings and memories for Snow, whose fiancé,Ronnie Raymond, was killed by the explosion. The team identifies the killer asKyle Nimbus, discovering that Nimbus does not control gases, but transforms his body into them. The team learns that Joe, the lead detective in the original case, is Nimbus' next target. Barry races to Iron Heights Prison to save Joe's life, forcing Nimbus to overexert himself so that he can apprehend him. The team locks Nimbus into a cell they have made. In a flashback to when the accelerator explodes, Wells is seen going into his hidden room and viewing a surveillance video of Barry getting struck by lightning in his lab and plans to make his move on his younger sister
in the present wells have a romantic dinner with belle