The Flash — “The Nuclear Man” — Image FLA113A_0059bc — Pictured: Robbie Amell as Ronnie — Photo: Cate Cameron/The CW — © 2015 The CW Network, LLC. All rights reserved.

The Flash — “The Nuclear Man” — Image FLA113A_0064bc — Pictured (L-R): Danielle Panabaker as Caitlin Snow, Grant Gustin as Barry Allen, and Robbie Amell as Ronnie — Photo: Cate Cameron/The CW — © 2015 The CW Network, LLC. All rights reserved.

The Flash — “The Nuclear Man” — Image FLA113A_0256b — Pictured (L-R): Danielle Panabaker as Caitlin Snow and Robbie Amell as Ronnie — Photo: Cate Cameron/The CW — © 2015 The CW Network, LLC. All rights reserved.

The Flash — “The Nuclear Man” — Image FLA113A_0263b– Pictured (L-R): Grant Gustin as Barry Allen and Danielle Panabaker as Caitlin Snow — Photo: Cate Cameron/The CW — © 2015 The CW Network, LLC. All rights reserved.

The Flash — “The Nuclear Man” — Image FLA113A_0307b — Pictured (L-R): Grant Gustin as Barry Allen, Tom Cavanagh as Harrison Wells, Carlos Valdes as Cisco Ramon, and Danielle Panabaker as Caitlin Snow — Photo: Cate Cameron/The CW — © 2015 The CW Network, LLC. All rights reserved.

The Flash — “The Nuclear Man” — Image FLA113A_0350b — Pictured: Carlos Valdes as Cisco Ramon — Photo: Cate Cameron/The CW — © 2015 The CW Network, LLC. All rights reserved.

The Flash — “The Nuclear Man” — Image FLA113A_0393bc — Pictured: Tom Cavanagh as Harrison Wells — Photo: Cate Cameron/The CW — © 2015 The CW Network, LLC. All rights reserved.

The Flash — “The Nuclear Man” — Image FLA113B_0020b — Pictured: Grant Gustin as Barry Allen — Photo: Cate Cameron/The CW — © 2015 The CW Network, LLC. All rights reserved.

The Flash — “The Nuclear Man” — Image FLA113B_0093b — Pictured: Victor Garber as Professor Stein — Photo: Cate Cameron/The CW — © 2015 The CW Network, LLC. All rights reserved.

The Flash — “The Nuclear Man” — Image FLA113B_0119b — Pictured: Victor Garber as Professor Stein — Photo: Cate Cameron/The CW — © 2015 The CW Network, LLC. All rights reserved.

The Flash — “The Nuclear Man” — Image FLA113B_0235b — Pictured (L-R): Carlos Valdes as Cisco Ramon and Jesse L. Martin as Detective Joe West — Photo: Cate Cameron/The CW — © 2015 The CW Network, LLC. All rights reserved.

The Flash — “The Nuclear Man” — Image FLA113B_0264b — Pictured: Chase Masterson as Sherry — Photo: Cate Cameron/The CW — © 2015 The CW Network, LLC. All rights reserved.

The Flash — “The Nuclear Man” — Image FLA113B_0354b — Pictured Carlos Valdes as Cisco Ramon — Photo: Cate Cameron/The CW — © 2015 The CW Network, LLC. All rights reserved.

The Flash — “The Nuclear Man” — Image FLA113C_0041b — Pictured (L-R): Danielle Panabaker as Caitlin Snow and Robbie Amell as Ronnie — Photo: Cate Cameron/The CW — © 2015 The CW Network, LLC. All rights reserved.

The Flash — “The Nuclear Man” — Image FLA113C_0085b — Pictured (L-R): Danielle Panabaker as Caitlin Snow and Grant Gustin as The Flash — Photo: Cate Cameron/The CW — © 2015 The CW Network, LLC. All rights reserved.

The Flash — “The Nuclear Man” — Image FLA113C_0089b — Pictured (L-R): Danielle Panabaker as Caitlin Snow and Grant Gustin as The Flash — Photo: Cate Cameron/The CW — © 2015 The CW Network, LLC. All rights reserved.

The Flash — “The Nuclear Man” — Image FLA113C_0125b — Pictured (L-R): Danielle Panabaker as Caitlin Snow and Robbie Amell as Ronnie — Photo: Cate Cameron/The CW — © 2015 The CW Network, LLC. All rights reserved.

The Flash — “The Nuclear Man” — Image FLA113C_0142b — Pictured: Danielle Panabaker as Caitlin Snow — Photo: Cate Cameron/The CW — © 2015 The CW Network, LLC. All rights reserved.

The Flash — “The Nuclear Man” — Image FLA113C_0185b — Pictured (L-R): Danielle Panabaker as Caitlin Snow and Grant Gustin as The Flash — Photo: Cate Cameron/The CW — © 2015 The CW Network, LLC. All rights reserved.

The Flash — “The Nuclear Man” — Image FLA113C_0193b — Pictured: Grant Gustin as The Flash — Photo: Cate Cameron/The CW — © 2015 The CW Network, LLC. All rights reserved.

The Flash — “The Nuclear Man” — Image FLA113C_0211b — Pictured (L-R): Danielle Panabaker as Caitlin Snow and Robbie Amell as Ronnie — Photo: Cate Cameron/The CW — © 2015 The CW Network, LLC. All rights reserved.

The Flash — “The Nuclear Man” — Image FLA113C_0216b — Pictured (L-R): Danielle Panabaker as Caitlin Snow and Robbie Amell as Ronnie — Photo: Cate Cameron/The CW — © 2015 The CW Network, LLC. All rights reserved.

Episode Description:

ROBBIE AMELL AND VICTOR GARBER GUEST STAR AS FIRESTORM — After Ronnie (Robbie Amell) attacks a physicist (Bill Dow), Barry (Grant Gustin) and the team realize they need to go after Caitlin’s (Danielle Panabaker) fiancé who is now a dangerous meta-human. They deduce the best way to track Ronnie is to find Dr. Martin Stein (guest star Victor Garber) 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 (Malese Jow), and Joe (Jesse L. Martin) enlists Cisco’s (Carlos Valdes) help to reinvestigate the murder of Nora Allen (Michelle Harrison). General Eiling (Clancy Brown) returns to Central City. Glen Winter directed the episode written by Andrew Kreisberg & Katherine Walczak.