This week's episode of "Penny Dreadful" will be a psychological treat for those who are fans of the genre as the show focuses on Vanessa (Eva Green), especially her mind. There, in the deep recesses of her mind, Vanessa reveals another dreadful demon who causes her so much fear.

The synopsis does not say much about what's going to happen in episode 4, which is titled "A Blade of Grass." All it says is that Vanessa will ask Dr. Seward (Patti LuPone) to perform hypnosis on her so she can go back in time.

The promo trailers, however, reveal enough to give viewers a peek, and what they show is this week will be quite intense as Vanessa journeys back into her past with her mind.

In one of the preview trailers, which is titled "Another Demon," Vanessa was seen in a dark room when John Clare (Rory Kinnear) entered and admonished her to eat. However, her lack of response left him exasperated, causing him to leave her and the food alone.

After he locked the door behind him, a voice hidden in the shadows asked Vanessa why she didn't eat. Hearing the voice surprised her because it was Dr. Seward. She was completely perplexed why she could see the doctor inside her room.

The doctor answered that her "mind is between both worlds," further explaining that Vanessa is in her office and also in a hospital cell, which suggests that all that was happening was actually not real but just in Vanessa's mind.

The scene was quite intense and dark where Vanessa said further in the conversation that she wanted to die because she was evil. "Satan had touched me, " she said with such disgust for herself. She also told the doctor that there's another demon haunting her, but when the doctor pressed her to reveal the identity of the demon, she said she didn't know who it was. The doctor continued to urge her to try but then the sound of the cell opening caused terror to fill Vanessa's face as she buries her face into her hands.

Who is that other creature? Will it be revealed in episode 4?

"Penny Dreadful" airs every Sunday, 10 P.M. EST on Showtime.