The Nuclear Man

Synopsis
After Ronnie attacks a physicist, Barry and the team realize they need to go after Caitlin's fiancé who is now a dangerous meta-human. They deduce the best way to track Ronnie is to find Dr. Martin Stein, who was working on a project called F.I.R.E.S.T.O.R.M.. Barry struggles to balance his duties as The Flash and his relationship with Linda Park, and Joe enlists Cisco's help to reinvestigate the murder of Nora Allen. General Eiling returns to Central City.

Main Characters

 * The Flash's Team
 * The Flash (Barry Allen)
 * Joe West
 * Cisco Ramon
 * Caitlin Snow
 * Harrison Wells (Eobard Thawne)
 * Linda Park
 * Eddie Thawne
 * Firestorm (Ronnie Raymond)
 * Firestorm (Martin Stein)
 * Iris West
 * Clarissa Stein

Villains

 * Reverse-Flash/Harrison Wells (Eobard Thawne)
 * United States Army
 * Wade Eiling
 * Sergeant Bates

Other Characters

 * Quentin Quale
 * Quentin Quale's Brother
 * Nora Allen
 * Sherry
 * Sherry's Ex-Husband
 * Albert Einstein
 * Linda Park's Father
 * Linda Park's Mother
 * Mal Duncan
 * Henry Allen
 * Gideon

Teams and Organizations

 * Central City Picture News
 * Taco Restaurant
 * The Flash's Team
 * STAR Labs
 * Brand and Paulson Convenience Store
 * CCPD
 * CC Jitters
 * 52nd and Waid Building
 * CCFD
 * Concordance Research
 * University of Chicago
 * Channel 52
 * Saved by The Flash
 * Central City-Starling City Train
 * FIRESTORM
 * Conway Prize for Scientific Advancement
 * Paper Clip
 * Big Belly Burger
 * United States Army
 * Rapid Respond Team

Species

 * Metahumans
 * Humans
 * Dogs
 * Vampires
 * Artificial Intelligence

Objects

 * The Flash Suit
 * Wheelchair
 * Wells: A Biography
 * Dark Matter
 * Firestorm Matrix
 * Firestorm Matrix Core
 * STAR Labs Mobile Research Unit
 * Super Light (Multispectrum Ultraviolet Laser Enhanced Scanner)
 * Hologram
 * Reverse-Flash Suit
 * Reverse-Flash Ring
 * Cisco-ed Treadmill
 * Tachyon Prototype
 * Reverse-Flash Ring
 * Firestorm Suit
 * Quantum Splicer

Locations

 * Earth-1
 * Earth
 * USA
 * Missouri
 * Central City
 * West House
 * CCPN Office
 * Unnamed Taco Restaurant
 * STAR Labs Central City Facility
 * STAR Labs Particle Accelerator
 * Time Vault
 * Brand and Paulson
 * Convenience Store
 * CC Jitters
 * Central City Police Precinct
 * 52nd and Waid
 * Building
 * Concordance Research Lab
 * Holly Drive
 * Allen House
 * Carson Station
 * Stein House
 * Paper Clip
 * Big Belly Burger
 * Badlands
 * Chicago
 * University of Chicago
 * Pedmont State Park
 * Hudson Falls
 * Wade Eiling's Facility

Trivia

 * The episode references the first issue of Firestorm in the comics.
 * This is the first episode where the transmutated form of Martin Stein and Ronnie Raymond is called Firestorm instead of the Burning Man.
 * In, it is stated that Martin Stein studied in Ivy University in 1975. However, Martin Stein states that he and Quentin Quale are classmates in the University of Chicago in 1974. Either this is a continuity error, or Martin Stein was transferred between 1974 and 1975.