A deadly illness sweeps through Starling City. When Diggle is struck down, Oliver confirms that the source of the illness is a new version of Vertigo. Tracking down a lead, Felicity is soon captured by The Count, who has escaped prison. Meanwhile, Moira fights for her life in the courtroom against a death sentence, and Laurel is forced to prosecute her when DA Donner is stricken down by the same illness.moreless
After Stephen decides to have some fun with his newfound powers, Jedikiah takes extreme measures to ensure it doesn't happen again.
John feels tension between himself and Cara after he and Russell return from their trip while Stephen decides to try and handle a dangerous new breakout on his own but finds himself in over his head and needing help from his fellow Tomorrow People.
Stephen becomes even more determined to find out what happened to his father after having a moment of clarity about him.
A.R.G.U.S. recruits Diggle to rescue Lyla, who has disappeared in Moscow following a lead on Deadshot. Oliver and Felicity volunteer to go with their friend, but run into trouble when Isabel insists on accompanying them. Meanwhile, Moira's attorney suggests that Thea stop dating Roy because it's hurting Moira's defense.moreless
Stephen and Russell head out for a night of fun only to run into a potential new breakout. They report back to John and Cara about the discovery but want to keep a low profile from ULTRA.
Russell learns of his father's death and struggles with the decision of whether or not to return home. John volunteers to go with him to keep him out of trouble.
Meanwhile Jedikiah has a secret that could destroy his career.
An assassin attacks Queen Manor in an attempt to kill Black Canary, who has taken refuge there with Oliver's help. Meanwhile, Moira is reluctant to make a guilty plea despite Thea's advice, and Oliver is furious when he discovers that Laurel will be prosecuting his mother in court.moreless
After Stephen breaks ULTRA protocol during a training exercise, Jedikiah's mysterious boss insists on meeting him. After learning Jedikiah is unable to help him Stephen turns to John who is only interested for selfish reasons.
Elsewhere Cara and John disagree on a dangerous plan when some of The Tomorrow People become desperate to attend a party in the outside world. And when Stephen again bails on plans with Astrid she decides to find out what he is really up to.
A new crime lord, the Mayor, arrives in Starling City and starts bring in illegal guns. When Oliver tires to counter with a Cash for Guns event, Black Canary's friend sin is hurt and the female heroine sets out for revenge. Meanwhile, Diggle links up with an old friend and DA Donner asks Laurel out on a date.moreless
When ULTRA's most wanted man Killian McCrane resurfaces after years in hiding Stephen enlists John's help in tracking him down. John agrees but changes his mind when he learn Killian isn't after Jedikiah as everyone first believed.
Stephen still wants to help but Cara explains the history between Killian and John: A history that brings back memories from John's past and forces him to do something he never thought he would ever do again.
Meanwhile Stephen's mom becomes suspicious of his whereabouts and activities placing him in an awkward position.
Officer Lance asks the Arrow for help in stopping a serial killer who goes after women, and Felicity volunteers to help. However, when their trap fails, the killer captures Laurel. Meanwhile, DA Adam Donner seeks the death penalty for Moira, and Oliver recruits Roy to help him find the Canary.moreless
Oliver goes after China White and her new partner, Bronze Tiger, when they interdict shipments of medicine intended for a hospital in the Glades. Meanwhile, Officer Lance captures Roy and Thea gives her boyfriend an ultimatum, while Laurel continues her hunt for the Arrow.moreless
Stephen looks to his fellow Tomorrow People for help when ultra attempts to scan his brain. John refuses to help forcing Cara to help Stephen secretly.
ULTRA and Stephen both search for a new break out who is using his powers to commit crimes. when an ULTRA SWAT team arrives stephen again calls on John, Cara and Russell for help.
John attempts to convince Stephen to spy on ULTRA while continuing the search for his missing father.
Diggle and Felicity go to Lian Yu and convince Oliver to return to Sterling City. Upon his return, he finds out that Isabel Rochev wants to take over Queen Consolidated. Thea is refusing to visit her mother in jail, Roy has stepped into Arrow's shoes and Laurel is trying to take down the vigilante. Flashbacks from the island show Shado, Slade, and Oliver in a difficult situation.moreless
When Stephen Jameson begins hearing voices and waking up in strange places he discovers he is a member of a highly evolved race of people with superhuman abilities. Seeking answers leads him to discover others of his kind called The Tomorrow People. He discovers The Tomorrow People are caught in a struggle for survival against an evil paramilitary group known as ULTRA who seek to destroy them all.
Stephen also learns there may be more to the mysterious disappearance of his father than he'd ever imagined and he discovers his own ties to Dr. Jedikiah Price, ULTRA's ruthless leader could be deadly.
When they discover Malcolm's plan, Oliver and Diggle try to stop him but lose Felicity to a police arrest. Meanwhile, Thea learns that Roy is in danger and goes to The Glades, endangering herself as well, while Oliver risks what's left of his friendship with Tommy for the sake of honesty. In the past, Oliver, Shado, and Slade try to stop Fyers from bringing down a passenger jet.moreless
The Dark Archer visits a seismologist to further The Undertaking. Meanwhile, Laurel makes a decision after Tommy tells her the truth, and Roy and Thea try to find The Hood. In flashback, Fyers tells the captive Oliver, Shado, and Slade of his plans for the missiles and for Yao Fei.moreless
Left with no one but Felicity to rely on, Oliver goes after an accountant and gets a lead on Walter's whereabouts. With Diggle out of his life, Oliver turns to Felicity for help in the field. Meanwhile, Tommy tells Laurel the truth about what he's doing, and Malcolm remembers working with Robert Queen and Frank Chen to alter The Glades forever after the death of his wife.moreless
Oliver and his team go after Deadshot, only to discover that ARGUS plans to capture the assassin... and recruit him as an operative. Meanwhile, Roy seeks out The Hood while Laurel inadvertently drives a further wedge between Oliver and Tommy. And on the island, Shado teaches Oliver how to use the bow.moreless
A woman at Oliver's club dies of Vertigo and Oliver confirms that The Count is apparently not responsible. However, when The Count escapes, Oliver sets out to bring him in and finds out who is really responsible for the drug distribution. Meanwhile, Quentin gets a lead that takes him to Tommy as the suspected distributor, and Tommy has to take extreme measures to prove his innocence. Meanwhile, on the island, Oliver continues his studies with Slade and Shado.moreless
Oliver's life is going smoothly for once... until the Huntress returns to town. Meanwhile, Thea gets Roy Harper at job at the new club just in time for its opening night, and Laurel and Quentin try to come to grips with Dinah's return.moreless
Deadshot is back and working with China White to kill Malcolm Merlyn. While Oliver goes after the two assassins, he struggles to help Tommy resolve his issues with his father and navigate a new relationship with old girlfriend McKenna.moreless
Oliver takes Felicity's advice and asks McKenna out on a date. Meanwhile, Thea befriends a pickpocket named Roy Harper, Moira takes on Malcolm, and a jewel thief who calls himself "Dodger" strikes at one of Oliver's friends.moreless
Diggle finds himself working with an unlikely ally when Felicity brings a wounded Oliver to the warehouse. As Oliver's life hangs in the balance he remembers his time on the island when he tried to escape with a new ally, Slade Wilson.moreless
Infamous criminal Cyrus Vanch plans to take on The Hood to reestablish his reputation as Starling City's leading crime lord. Meanwhile, Oliver confronts his mother over the copy of the list that Walter found, and Quentin unintentionally endangers Laurel.moreless
Oliver hunts down a drug dealer known as "The Count" to prevent the distribution of a new drug known as Vertigo... after Thea has been arrested for using it. While Oliver turns to a former girlfriend and current vice cop for help, Moira defends Thea and Felicity learns more about Moira.moreless
Oliver and Diggle are at odds when Diggle's former commanding officer is next on the list. Meanwhile, Thea notices when Moira and Malcolm spend time together, while Tommy and Laurel have dinner with Tommy's father.moreless
When he discovers that Moira and Thea stopped celebrating Christmas since his disappearance, Oliver tries to throw a Queen Christmas party. Meanwhile, Tommy and Laurel disagree on how they should spend Christmas together.moreless
Oliver takes Helena under his wing and trains her in the life of a street vigilante. However, Diggle has concerns about Helena, concerns that soon prove true when Helena kills the head of the Triad and puts herself and Oliver at risk.moreless
Oliver meets a kindred spirit: the daughter of a mobster who has her own desire for vengeance. Meanwhile, Tommy turns to Laurel for help.
When an off-duty officer is wounded by bank robbers calling themselves the Royal Flush Gang, Diggle tries to convince Oliver that he must do more than go after the men on his father's list. Meanwhile, Tommy asks Thea for dating advice and Moira demands to know why Oliver keeps disappearing.moreless