Arrow — “Dark Waters” — Image AR409A_0010b.jpg — Pictured: Stephen Amell as Oliver Queen — Photo: Diyah Pera/ The CW — © 2015 The CW Network, LLC. All Rights Reserved.

Arrow — “Dark Waters” — Image AR409A_0133b.jpg — Pictured: Emily Bett Rickards as Felicity Smoak — Photo: Diyah Pera/ The CW — © 2015 The CW Network, LLC. All Rights Reserved.

Arrow — “Dark Waters” — Image AR409A_0149b.jpg — Pictured (L-R): Katie Cassidy as Laurel Lance and Emily Bett Rickards as Felicity Smoak — Photo: Diyah Pera/ The CW — © 2015 The CW Network, LLC. All Rights Reserved.

Arrow — “Dark Waters” — Image AR409A_0167b.jpg — Pictured: Katie Cassidy as Laurel Lance — Photo: Diyah Pera/ The CW — © 2015 The CW Network, LLC. All Rights Reserved.

Arrow — “Dark Waters” — Image AR409A_0175b.jpg — Pictured: Stephen Amell as Oliver Queen — Photo: Diyah Pera/ The CW — © 2015 The CW Network, LLC. All Rights Reserved.

Arrow — “Dark Waters” — Image AR409A_0209b.jpg — Pictured: Stephen Amell as Oliver Queen — Photo: Diyah Pera/ The CW — © 2015 The CW Network, LLC. All Rights Reserved.

Arrow — “Dark Waters” — Image AR409A_0228b.jpg — Pictured: Stephen Amell as Oliver Queen — Photo: Diyah Pera/ The CW — © 2015 The CW Network, LLC. All Rights Reserved.

Arrow — “Dark Waters” — Image AR409A_0252b.jpg — Pictured: Willa Holland as Thea Queen — Photo: Diyah Pera/ The CW — © 2015 The CW Network, LLC. All Rights Reserved.

Arrow — “Dark Waters” — Image AR409A_0278b.jpg — Pictured: Katie Cassidy as Laurel Lance — Photo: Diyah Pera/ The CW — © 2015 The CW Network, LLC. All Rights Reserved.

Arrow — “Dark Waters” — Image AR409A_0402b.jpg — Pictured: David Ramsey as John Diggle — Photo: Diyah Pera/ The CW — © 2015 The CW Network, LLC. All Rights Reserved.

Arrow — “Dark Waters” — Image AR409B_0034b.jpg — Pictured: Emily Bett Rickards as Felicity Smoak — Photo: Diyah Pera/ The CW — © 2015 The CW Network, LLC. All Rights Reserved.

Arrow — “Dark Waters” — Image AR409B_0042b.jpg — Pictured (L-R): Charlotte Ross as Donna Smoak and Paul Blackthorne as Detective Quentin Lance — Photo: Diyah Pera/ The CW — © 2015 The CW Network, LLC. All Rights Reserved.

Arrow — “Dark Waters” — Image AR409B_0071b.jpg — Pictured (L-R): David Ramsey as John Diggle, Echo Kellum as Curtis Holt and Chenier Hundal as Paul — Photo: Diyah Pera/ The CW — © 2015 The CW Network, LLC. All Rights Reserved.

Arrow — “Dark Waters” — Image AR409B_0076b.jpg — Pictured (L-R): Echo Kellum as Curtis Holt, Chenier Hundal as Paul and Emily Bett Rickards as Felicity Smoak — Photo: Diyah Pera/ The CW — © 2015 The CW Network, LLC. All Rights Reserved.

Arrow — “Dark Waters” — Image AR409B_0132b.jpg — Pictured: David Ramsey as John Diggle — Photo: Diyah Pera/ The CW — © 2015 The CW Network, LLC. All Rights Reserved.

Arrow — “Dark Waters” — Image AR409B_0208b.jpg — Pictured: Emily Bett Rickards as Felicity Smoak — Photo: Diyah Pera/ The CW — © 2015 The CW Network, LLC. All Rights Reserved.

Arrow — “Dark Waters” — Image AR409B_0224bc.jpg — Pictured (L-R): Stephen Amell as Oliver Queen and Emily Bett Rickards as Felicity Smoak — Photo: Diyah Pera/ The CW — © 2015 The CW Network, LLC. All Rights Reserved.

Arrow — “Dark Waters” — Image AR409B_0320b.jpg — Pictured (L-R): Neal McDonough as Damien Darhk and Stephen Amell as Oliver Queen — Photo: Diyah Pera/ The CW — © 2015 The CW Network, LLC. All Rights Reserved.

Arrow — “Dark Waters” — Image AR409B_0359b.jpg — Pictured (L-R): David Ramsey as John Diggle, Willa Holland as Thea Queen, Neal McDonough as Damien Darhk and Emily Bett Rickards as Felicity Smoak — Photo: Diyah Pera/ The CW — © 2015 The CW Network, LLC. All Rights Reserved.

Official Synopsis:

“Dark Waters” — (8:00-9:00 p.m. ET) (TV-14, LV) (HDTV)

OLIVER TAKES ON HIVE — After the city is attacked again, Oliver (Stephen Amell) makes a bold move against HIVE. Malcolm (John Barrowman) checks in on Thea (Willa Holland) and leaves her with a warning. Things take a horrible turn when Damien Darhk (guest star Neal McDonough) retaliates in a brutal manner at Oliver’s mayoral holiday party. John Behring directed the episode written by Wendy Mericle & Ben Sokolowski (#409).  Original airdate 12/9/2015.