There was serious doubt about ARROW returning for a fourth season. Rumors were circulating the show's star Stephen Amell would not return, or that the show would undergo a major transformation and have more of an emphasis on Team Arrow, rather than the main character. For this reason, the conclusion of the show's third season seemed like a series finale. But, ratings and profit margins dictated ARROW return for at least one more season, and the fourth season will feature a plethora of new plotlines, heroes and villains.
Oliver's sister Thea (Will Holland) is set to take up her mantle as Speedy. While Roy Harper is speedy in the comics, the character will add a yellow cape to the ensemble and harken back to Arrow's second helper Mia Dearden, who has not been introduced in the TV show. Thea was however, resurrected from the Lazarus Pit, and most people who go through the process do not come out the same way. It's a Stephen King PET SEMETARY type of thing. Speculation is that Thea may eventually become the "Red Hood", though that character was already introduced on Gotham.
And, if you remember the short-lived TV series BIRDS OF PREY, it's likely ARROW will reintroduce the female crime fighting league this season. The Birds of Prey include the Black Canary, Katana and The Huntress, all of whom have appeared on ARROW and are scheduled for repeat performances in season four. Though the original series never found an audience and was short-lived, I rather enjoyed it and thought it was well done. There were a multitude of Batman references, and in a few episodes, the Caped Crusader made a cameo appearance in silhouette form.
Diggle, played by David Ramsey, will finally get a costume and assume the comic character The Guardian. Since The Guardian relies on his military training and doesn't have super powers per se, he'll receive an indestructible shield from Star labs in another cross-over between ARROW and THE FLASH. This will make him D.C.'s version of Captain America.
THE FLASH was better scripted than ARROW last season, and was certainly better than the second season of ARROW, which almost doomed the show. With greater scripting, especially from Geoff Johns and the continuation of cross-over storylines, ARROW is poised to be a strong contender for fan approval in its fourth season.