American crime drama television series "Gotham" season 4 will soon return on the small screens for the second half of season 4. Spoilers reveal that the upcoming season will be about "The Long Halloween."

In the midseason finale, it featured the return of Jerome (Cameron Monaghan) who apparently needs Penguin (Robin Lord Taylor) to make his triumphant comeback. During the welcome party of Penguin in Arkham Asylum, he saw a familiar face. Jerome, who will become Joker, has gory stitches on the face and a sickly smile. Contrary to what everyone believes, Jerome is not dead. It appears that Jerome was just in prison, while preparing to return to his villainous ways in Gotham City.

Since the two met up, there is a possibility that they will work together in the season's return. This means that Jim Gordon (Ben McKenzie) and the rest of the heroes of Gotham will be facing different terrors. The city will be in danger since Joker and Penguin will be recruiting other villains to join them.

Actor Monaghan, who plays Joker, posted an image on Twitter that teases the storyline for "Gotham." It features Joker, Penguin, Scarecrow, Solomon Grundy, Poison Ivy, Catwoman, and Mad Hatter sitting around an office. Joker has a speech bubble that says, "Trick or Treat?"

The image is from the 1996 comic "Batman: The Long Halloween" created by Jeph Loeb and Tim Sale. Monaghan captioned the picture saying, "It's not Halloween. So why am I posting this? #subtle" Fans believe that the actor is hinting that the new installment will be about the "Long Halloween."

ComicBook notes that this is possible since the roster of characters is already in the series. The ones in the photo that Monaghan shared already worked together on the show. With Jerome and Penguin's partnership, it is even easier to gather these villains. With the looks of it, Gotham will indeed be in big trouble.

"Gotham" season 4 returns this Spring on Fox.