"Arrow" season 4 episode 5, titled "Haunted," will bring back Matt Ryan as John Constantine to help Oliver Queen (Stephen Amell) save Sara Lance's (Caity Lotz) soul. Sara was previously revived by the Lazarus Pit yet her resurrection came with a few side effects, causing her to become violent and insane.

Ryan previously played the role in the NBC series "Constantine" but the series was cancelled after just one season. This episode will serve as a chance for fans to get one more glimpse of Constantine in action.

Given Constantine's specialty with the mystical and paranormal, he may be Team Arrow's only option in reversing the effects of the Lazarus Pit and restoring Sara back to her normal self. It is possible that the "restored" albeit damaged version of Sara is what fans will encounter when she joins next year's spin-off show, "Legends of Tomorrow."

Damien Darhk (Neal McDonough), the primary villain for season 4, is also shown in the promotional trailer, where he advises Team Arrow to just kill Sara and put her back in the grave, given that she is no longer the same person as she was before her death. 

In related news, the episode was previously leaked just a few days before its scheduled release. According to a report from Variety, the episode had been downloaded on piracy sites more than 11,000 times by Monday, Nov. 2. However, the copy of the episode is reportedly meant for screeners and lacks special effects and proper editing.

Variety notes that the leak will not gravely affect the ratings for the episode despite how popular shows like "Arrow" and "The Flash" are in terms of online piracy. This is in contrast to shows such as "Game of Thrones," which holds the record as the most pirated show within a 24-hour window.

"Arrow" season 4 episode 5 airs today, Nov. 4.