Original air date: 10/29/2014 Runtime: 42:27 min. A furious Nyssa al Ghul (recurring guest star KATRINA LAW) returns to Starling City and confronts Oliver about Sara’s death. When Oliver learns Malcolm Merlyn is alive, he suspects Merlyn killed Sara. Oliver and Nyssa join forces and go after the Dark Archer, intent on bringing Sara’s killer to justice. Laurel keeps her distance from Nyssa, however, as she blames her sister’s death on her involvement with the League of Assassins. Meanwhile, Oliver and Roy work on repairing their respective relationships with Thea, who has returned home. Nyssa discusses Oliver with her father, Ra’s al Ghul (guest star MATT NABLE).
Original air date: 11/05/2014 Runtime: 42:34 min. When a cyber attack brings Starling City to its knees, Oliver and Felicity are pushed to their limits to contain the destruction. Life gets even more complicated for Felicity when her mother, Donna (guest star CHARLOTTE ROSS), stops by for a surprise visit. Meanwhile, Ted Grant (guest star J.R. RAMIREZ) questions Laurel’s motives, and Thea buys an apartment with Malcolm’s “estate” money, which infuriates Oliver. NOLAN FUNK guest stars as Felicity’s ex-boyfriend.
Original air date: 11/12/2014 Runtime: 42:32 min. After a body is found strung up in the Wildcat gym, Ted Grant becomes the main suspect. Oliver and Laurel argue over Ted’s innocence. Meanwhile, in flashbacks, when Maseo needs Oliver to remember where an informant for China White stashed key information, he asks Tatsu (guest star RILA FUKUSHIMA) to help jog Oliver’s memory. Roy shares a secret with Felicity.
Original air date: 11/19/2014 Runtime: 42:30 min. Oliver must stop an Arrow-obsessed serial killer, Carrie Cutter (guest star AMY GUMENICK), who is convinced that The Arrow is her one true love and will stop at nothing to get his attention. Unfortunately, her way of getting his attention is to kill people. Meanwhile, Ray asks Felicity to be his date for a work dinner with important clients. Thea auditions new DJs for Verdant and meets Chase (guest star AUSTIN BUTLER), a brash DJ with whom she immediately clashes.
Original air date: 12/03/2014 Runtime: 42:04 min. In part two of the Arrow/Flash crossover event, Oliver, Arsenal and Diggle track down the location of a boomerang-wielding killer named Digger Harkness (guest star NICK E. TARABAY) but are surprised when they come face to face with an A.R.G.U.S. team. Diggle asks Lyla why A.R.G.U.S. is involved, but she defers until Harkness attacks the building, killing several agents and targeting Lyla. The Arrow joins the fight and gets help from an old friend – The Flash (guest star GRANT GUSTIN). Harkness manages to get away and Oliver teams up with Barry again to find him before he can get to Lyla. When Harkness plants five bombs in the city that are timed to explode at the same time, both teams must come together to save the city.
Original air date: 12/10/2014 Runtime: 42:33 min. Nyssa al Ghul returns to Starling City and tells Oliver that her father, Ra’s al Ghul has given Oliver 48 hours to find Sara’s killer or the League of Assassins will start killing the citizens of Starling City. Laurel is stunned when her father delivers a very special Christmas gift – her mother, Dinah (recurring guest star ALEX KINGSTON). Meanwhile, Ray tries to make amends with Felicity and Oliver sets a meeting with Ra’s al Ghul.
Original air date: 01/28/2015 Runtime: 42:34 min. Arsenal and Diggle confront Laurel about trying to fight in her sister’s shoes and warn her to stop before she gets herself killed. However, when Brick (guest star VINNIE JONES) kidnaps the city’s Aldermen and threatens to kill them all unless the police evacuate The Glades, it’s all suits on deck. Meanwhile, Ray steps in to help Lance and the police force fight Brick – showing Felicity a new side of her boss. Malcolm tells Thea that Ra’s al Ghul is after him and his family and they must leave town immediately.
Original air date: 04/29/2015 Runtime: 41:45 min. As Oliver goes through a rigorous transformation, the League of Assassins sets their sights on Nyssa, who is back in Starling City training Laurel. When Nyssa realizes they are coming, she arms up to face them alone but Laurel asks Felicity and Diggle to help protect her new friend.