The Flash -- "Grodd Lives" -- Image FLA121B_0131b -- Pictured: Rick Cosnett as Detective Eddie Thawne -- Photo: Cate Cameron/The CW -- © 2015 The CW Network, LLC. All rights reserved.

The Flash -- "Grodd Lives" -- Image FLA121B_0151b -- Pictured: Rick Cosnett as Detective Eddie Thawne -- Photo: Cate Cameron/The CW -- © 2015 The CW Network, LLC. All rights reserved.

The Flash -- "Grodd Lives" -- Image FLA121B_0235b -- Pictured (L-R): Tom Cavanagh as Harrison Wells and Rick Cosnett as Detective Eddie Thawne -- Photo: Cate Cameron/The CW -- © 2015 The CW Network, LLC. All rights reserved.

The Flash -- "Grodd Lives" -- Image FLA121A_0072b -- Pictured: Grant Gustin as The Flash -- Photo: Cate Cameron/The CW -- © 2015 The CW Network, LLC. All rights reserved.

The Flash -- "Grodd Lives" -- Image FLA121A_0078b -- Pictured: Grant Gustin as The Flash -- Photo: Cate Cameron/The CW -- © 2015 The CW Network, LLC. All rights reserved.

The Flash -- "Grodd Lives" -- Image FLA121A_0079b -- Pictured: Grant Gustin as The Flash -- Photo: Cate Cameron/The CW -- © 2015 The CW Network, LLC. All rights reserved.

The Flash -- "Grodd Lives" -- Image FLA121A_0085b -- Pictured: Grant Gustin as The Flash -- Photo: Cate Cameron/The CW -- © 2015 The CW Network, LLC. All rights reserved.

The Flash -- "Grodd Lives" -- Image FLA121A_0108b -- Pictured: Jesse L. Martin as Detective Joe West -- Photo: Cate Cameron/The CW -- © 2015 The CW Network, LLC. All rights reserved.

The Flash -- "Grodd Lives" -- Image FLA121A_0138b -- Pictured (L-R): Jesse L. Martin as Detective Joe West, Grant Gustin as Barry Allen, Carlos Valdes as Cisco Ramon -- Photo: Cate Cameron/The CW -- © 2015 The CW Network, LLC. All rights reserved.

The Flash -- "Grodd Lives" -- Image FLA121A_0205b -- Pictured (L-R): Jesse L. Martin as Detective Joe West and Grant Gustin as Barry Allen -- Photo: Cate Cameron/The CW -- © 2015 The CW Network, LLC. All rights reserved.

The Flash -- "Grodd Lives" -- Image FLA121A_0209b -- Pictured (L-R): Jesse L. Martin as Detective Joe West, Carlos Valdes as Cisco Ramon, and Grant Gustin as Barry Allen -- Photo: Cate Cameron/The CW -- © 2015 The CW Network, LLC. All rights reserved.

The Flash -- "Grodd Lives" -- Image FLA121A_0218b -- Pictured: Carlos Valdes as Cisco Ramon -- Photo: Cate Cameron/The CW -- © 2015 The CW Network, LLC. All rights reserved.

The Flash -- "Grodd Lives" -- Image FLA121A_0248b -- Pictured (L-R): Grant Gustin as Barry Allen and Carlos Valdes as Cisco Ramon -- Photo: Cate Cameron/The CW -- © 2015 The CW Network, LLC. All rights reserved.

The Flash -- "Grodd Lives" -- Image FLA121B_0148b -- Pictured: Tom Cavanagh as Harrison Wells -- Photo: Cate Cameron/The CW -- © 2015 The CW Network, LLC. All rights reserved.

The Flash -- "Grodd Lives" -- Image FLA121SG_033.090.007 -- Pictured (L-R): Grodd and Jesse L. Martin as Detective Joe West -- Photo: The CW -- © 2015 The CW Network, LLC. All rights reserved.

The Flash -- "Grodd Lives" -- Image FLA121_SG_049.020.001 -- Pictured (L-R): Grodd and Grant Gustin as Barry Allen / The Flash -- Photo: The CW -- © 2015 The CW Network, LLC. All rights reserved.

The Flash -- "Grodd Lives" -- Image FLA121B_0081b -- Pictured (L-R): Rick Cosnett as Detective Eddie Thawne and Tom Cavanagh as Harrison Wells -- Photo: Cate Cameron/The CW -- © 2015 The CW Network, LLC. All rights reserved.

The Flash -- "Grodd Lives" -- Image FLA121B_0120b -- Pictured (L-R): Rick Cosnett as Detective Eddie Thawne and Tom Cavanagh as Harrison Wells -- Photo: Cate Cameron/The CW -- © 2015 The CW Network, LLC. All rights reserved.

The Flash -- "Grodd Lives" -- Image FLA121B_0130bc -- Pictured (L-R): Rick Cosnett as Detective Eddie Thawne and Tom Cavanagh as Harrison Wells -- Photo: Cate Cameron/The CW -- © 2015 The CW Network, LLC. All rights reserved.