New spoilers reveal that "Arrow" fans will have a lot to look forward to when the series returns to The CW this fall, including the possible return of Roy and Sara Lance.

During the Season 3 finale, Oliver defeated Ra's al Ghul, the leader of the League of Assassins, and saved Starling City from destruction. Malcolm Merlin then stepped up as Ra's successor, while Thea adopted a new superhero identity as Speedy. In addition, at the very end Oliver decided to hang up his hood and drive off into the sunset with Felicity.

Although the finale ended on a good note, Oliver and Felicity left the rest of Team Arrow to defend Starling City by themselves. That means that the weight of protecting the city has fallen upon Laurel, Diggle and Thea. However, series star Stephen Amell teased that a problem with Thea will lure Oliver out of retirement and back to the city.

When asked to sum up the Season 4 premiere in three words on Twitter Thursday, Amell tweeted "What's wrong Speedy?" This suggests that his sister, Thea, will be in need of help or guidance and will be a focal point in the season premiere.

Last season, Thea was killed by Ra's al Ghul and then resurrected from the dead through the Lazarus Pit. Thea also suffered from the heartache of losing her lover, Roy, when he decided to flee Starling City in order to protect Oliver. However, actress Emily Bett Rickards, who plays Felicity, hinted that Roy may possibly return and reunite with Thea.

"I'd like to see [Felicity] and Oliver work together as a couple. I want them to be team players together... [to] see if they can help the Thea, help the Roy," Rickards said, reports Melty.

Another game-changing moment in Season 3 occurred during when Laurel Lance watched her sister, Sara, die. The tragedy pushed Laurel to embrace her destiny and become the Black Canary. While speaking at the Las Vegas Comic-Con this past weekend, actor John Barrowman suggested that the Lance sisters will be reunited once again. He also revealed that he will reprise his role as Malcolm Merlyn in the upcoming season.

"We start filming in July, Season 4. I just finalized my deal about a week ago so... it was just about working out dates and stuff," said Barrowman, according to ComicsAlliance. "So, I'm very excited about going back. I can't tell you anything, because I do know a bit of what's gonna happen, but if you love Malcolm Merlyn, if you love Oliver Queen, if you love Thea Queen, if you love the Canary sisters ... I say that with a bit of a twist and a joke, you're gonna love what's gonna happen across the DC world."

A trailer for the new spin-off series "Legends of Tomorrow" also teased that Sara will be brought back to life by the Lazarus Pit and then fight with Vandal Savage and his army. Before the series debuts in 2016, however, she may pop up in Season 4 of Arrow since it has not been confirmed whether her resurrection will happen in the new series or during "Arrow."

When Sara is finally revived, Cinema Blend reports that she will take the White Canary identity.

Furthermore, TVLine revealed that an African American male in his 20s with technological skills that meet Felicity's level.