The Nuclear Man

"He's not even Ronnie anymore. He's Martin Stein walking around in Ronnie's body, like a vampire."

- Caitlin Snow

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 FIRESTORM 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.

Protagonists

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

Antagonists

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

Other Characters

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

Teams and Organizations

 * Big Belly Burger
 * CC Jitters
 * Central City Fire Department
 * Central City Picture News
 * Central City Police Department
 * Central City-Starling City Train
 * Channel 52
 * Concordance Research
 * Conway Prize for Scientific Advancement
 * FIRESTORM
 * Paper Clip
 * S.T.A.R. Labs
 * Saved by The Flash
 * The Flash's Team
 * United States Army
 * Rapid Respond Team
 * University of Chicago

Events

 * Reverse-Flash's War
 * Rescue of Firestorm

Species

 * Artificial Intelligence
 * Dogs
 * Humans
 * Metahumans
 * Vampires

Objects and Concepts

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

Locations

 * Earth-1
 * Earth
 * United States of America
 * Chicago
 * University of Chicago
 * Pedmont State Park
 * Hudson Falls
 * Missouri
 * Badlands
 * Central City
 * 52nd and Waid
 * Big Belly Burger
 * Brand and Paulson
 * Carson Station
 * CC Jitters
 * Central City Police Precinct
 * Concordance Research Lab
 * Holly Drive
 * Allen Residence
 * Paper Clip
 * S.T.A.R. Labs Central City Facility
 * S.T.A.R. Labs Particle Accelerator
 * Time Vault
 * Stein Residence
 * Central City Picture News Office
 * West House
 * Wade Eiling's Facility