The mystery of Ray Palmer's disappearance is at the center of "Lost Souls," next week's episode of "Arrow."

When Oliver and company receive news indicating that the Atom may yet be alive, Team Arrow formulates a plan to save their friend from whoever -- or whatever -- is holding him captive.

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The episode's official synopsis reads:

RAY PALMER RETURNS FROM THE DEAD - Felicity (Emily Bett Rickards) is frantic when she learns that Ray (guest star Brandon Routh) is alive and being held by Damien Darhk (guest star Neal McDonough). Felicity's guilt over not finding Ray sooner causes tension between her and Oliver (Stephen Amell). Meanwhile, Sara (guest star Caity Lotz) joins Laurel (Katie Cassidy), Thea (Willa Holland) and the team on a rescue mission for Ray. However, the effects of the Lazarus Pit take over and threaten to jeopardize the entire operation. Donna Smoak (guest star Charlotte Ross) returns to Star City. Antonio Negret directed the episode written by Beth Schwartz & Emilio Ortega Aldrich (#406).

"Arrow" airs Wednesdays at 8 p.m. on The CW.