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 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 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 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 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 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 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 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 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 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.

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 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 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 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 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 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 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 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 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.