Merve is a young woman struggling to overcome the various difficulties she faces in the prime of her life. Unable to achieve success in any of the jobs she takes on, Merve becomes a laughingstock among the wealthy. Determined to put an end to this situation and lead a respectable life, she turns to a marriage of convenience as a solution. However, when she falls in love with someone else, things become complicated. Unwilling to choose between love and money, Merve finds herself utterly helpless due to the marriage contract she signed. Now, there is only one solution left for her: to kill her husband.

Cabbar and a cursed family are drawn into the labyrinth of a mansion haunted by a dark legacy, a place where secrets and eerie entities have reigned for years. Cabbar is the last representative of a tradition of dhikr (remembrance of God) that dates back to the Ottoman era. His only weapons in his battle with the demonic realm are his talismanic armor and powerful dhikr. Ignoring his lawyer's warnings, Hasan moves into the mansion he has inherited. Soon, his daughter Elif hears children's whispers in the middle of the night, and his wife Esma sees bloody silhouettes. As the curtain of mystery in Number 303 is lifted, Cabbar will pay a heavy price for his struggle to save his family.