Yasak Elma started out being the story of Yıldız and Zeynep, two sisters, who are very close but have very different characters and life goals. Zeynep is a girl who strictly adheres to her ethical values, aims to have a successful career and strives for it; while Yıldız believes that she deserves more and considers happiness to be a marriage with a rich man, who would save her from her low-income life. Now in season 4 the focus is on the female leads. Yıldız and Ender has gone from enemies, to best friends, to enemies, friends and now enemies again. This is for a very large part the result of her mother Asuman who with her meddling and ambitions has ruined Yıldız life. Yıldız is now facing Ender who has now joined forces with her arch nemesis Sahika. This despite the fact that Sahika cost Ender the love of her life. But vengeance and ambitions are more important.
While Hasan Ali is trying to get over his astonishment that he married Şahika, he does his best to end this marriage. However, Şahika will not keep her promise. As Cansu struggles to disrupt Çağatay and Yıldız, an unexpected visitor changes the course of events. (This little editor is hoping for a surprise return from Kerim but knows she will not be getting her YIlKer back)