Oliver assembles a group of unlikely allies - Slade, Nyssa, Merlyn and Digger Harkness - to engage in an epic battle against Chase and his army.

Black Siren returns to help Chase; Felicity organizes a birthday party for Oliver; Lance is furious when Rene misses the custody hearing for his daughter.

Oliver faces the forced release of dozens of violent criminals prosecuted by Adrian Chase; a crate arrives at Oliver's office containing a mysterious corpse encased in concrete.

The situation gets intense when Oliver and Felicity are trapped in the bunker together; Lyla and Diggle deal with their martial issues.

Oliver, Team Arrow, ARGUS and the SCPD kick off a citywide manhunt for Adrian Chase; Felicity needs to deliver something illegal that will entice Helix to go after Chase.

Oliver's decision to call the Bratva for help taking down Prometheus surpises Diggle and Felicity; Felicity makes a shocking discovery at Helix.

Oliver and Thea are concerned when a family friend plans to run for mayor; Thea starts to exhibit side effects from the Lazarus Pit; Felicity asks an employee for help with a business decision.

Prometheus attempts to break Oliver; Anatoly worries about Oliver's increasingly violent tendencies, which come to a head in a brutal confrontation.

Oliver gets closer to the truth about Prometheus; Helix refuses to continue helping Felicity until she does a favor for them.

When Vigilante attacks Oliver while he's acting as the mayor, Diggle leads the team on a mission to stop Vigilante once and for all.

China White, Cupid and Liza Warner escape Iron Heights and set out for Star City; the ACU seeks to arrest the Green Arrow for Detective Malone's murder.

An attack on City Hall brings back painful memories for Rene; flashbacks reveal Rene's transformation from family man to a hero named Wild Dog; Oliver realizes the best way to find the attacker is to do so as Mayor Queen.

A mission takes Oliver, Felicity and the team to Russia, where they meet up with Anatoly, Oliver's old friend; fresh out of rehab, Lance returns to the mayor's office ready to get back to work.

Oliver gets help from a surprising source in his quest to take down Kovar; Felicity tries to hack the NSA to help free Diggle; Curtis informs the team about a female vigilante wreaking havoc all over the country.

Oliver worries that Prometheus is right and really is a killer at heart; Felicity is bent on revenge after Detective Malone's murder; Diggle fights for his life in prison.

After the attack on Curtis, Oliver realizes Prometheus is planning to make a deadly move on all of Team Arrow; Felicity and Malone find a clue that ties Prometheus to Oliver's past.

Oliver wakes up to a life in which his parents are still alive and he is about to marry Laurel; Felicity faces a new threat with the help of The Flash and Supergirl.

Oliver learns about a new vigilante in Star City after the bodies of two criminals show up at SCPD; Diggle feels annoyed about his new situation; Lance confesses a shocking secret to Thea; in flashbacks, Oliver speaks with Konstantin Kovar.

Oliver searches for connections between Prometheus' victims; Felicity and Curtis discover the victims are all tied to Oliver's past; Thea has a talk with Lance; Felicity thinks about telling Malone the truth about her work.

Oliver joins Lyla on a secret mission for Diggle while Felicity opts to stay behind; Tobias Church launches a deadly assault against the city.

Wild Dog defies the Green Arrow's orders by taking it upon himself to go after drug dealer Garret Runnels, who is terrorizing Star City.

At 11, Barry Allen's life changed completely when his mother died in a freak accident and his innocent father was convicted of her murder. Now a crime-scene investigator, his dedication to learn the truth about his mother's death drives him to follow up on every new scientific advancement and urban legend. When his latest obsession -- a particle accelerator heralded as a world-changing invention -- causes an explosion, it creates a freak storm and Barry is struck by lightning. He awakes from a coma nine months later with the power of superspeed. When he learns that others who have gained powers use them for evil, he dedicates himself to protecting the innocent, while still trying to solve the older mystery.

At 12 years old, Kara Zor-El escapes doom on planet Krypton to find protection on Earth with the Danver family, where she grows up in the shadow of her foster sister, Alex, and learns to hide the extraordinary powers she shares with her cousin, Superman. Now an adult living in National City and working for media mogul Cat Grant, Kara finds her days of keeping her abilities a secret are over when super-secret agency head Hank Henshaw enlists her to help protect the city's citizens from threats. Finally coming into her own, Kara must juggle her new responsibilities with her very human relationships.

"Arrow" and "The Flash" have some new superhero company in the CW's lineup with the addition of "DC's Legends of Tomorrow." After seeing what doom the future holds, time-traveling rogue Rip Hunter realizes heroes alone are not enough to prevent the impending catastrophe that threatens not only the planet, but all of time itself. Tasked with recruiting both heroes and villains, Rip brings together a ragtag team of divergent talents, which includes the likes of Sara Lance, Ray Palmer, and Heat Wave.

CW and Greg Berlanti expand the footprint of their DC Comics universe with this exploration of the intersection between family life and being a superhero. As a younger man, Jefferson Pierce donned the suit of a vigilante and protected the streets of his city, but he believed he'd left those days in the past. He learns that life doesn't always work out as planned when his daughter, Jennifer -- a star student who is determined to achieve justice at any cost -- gets recruited by a street gang. In order to protect his family, Jefferson sees no choice but to once again become Black Lightning.

James Gordon is a rising detective in the dangerously corrupt Gotham City, where his late father was a successful district attorney. Brave, honest and determined to prove himself, Gordon must navigate the dirty politics of Gotham's justice system as well as the rise of malevolent villains like The Penguin, The Riddler and Catwoman. The series also chronicles the life of young Bruce Wayne, who becomes an orphan when his billionaire parents Thomas and Martha Wayne are murdered. Gordon becomes a friend to young Bruce as he finds his way toward becoming the iconic caped crusader.

Phil Coulson (Clark Gregg, reprising his role from "The Avengers" and "Iron Man" ) heads an elite team of fellow agents with the worldwide law-enforcement organization known as SHIELD (Strategic Homeland Intervention Enforcement and Logistics Division), as they investigate strange occurrences around the globe. Its members -- each of whom brings a specialty to the group -- work with Coulson to protect those who cannot protect themselves from extraordinary and inconceivable threats, including a formidable group known as Hydra.