After Ronnie attacks a physicist, Barry and the team realizethey need to go after Caitlin's fiancé who is now a dangerousmeta-human. They deduce the best way to track Ronnie is to findDr. Martin Stein who was working on a project calledF.I.R.E.S.T.O.R.M. Barry struggles to balance his duties as TheFlash and his relationship with Linda Park, and Joe enlistsCisco's help to reinvestigate the murder of Nora Allen.
