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.
After sleeping with Cansu, Çağatay tries to make things right with Yıldız. Unaware that Yıldız continues to meet with Cansu; Çağatay looks for ways to get Cansu away from them. Ender and Şahika decide to make more damaging plans as they are tired of being hit by Hasan Ali. However, it will be Şahika, who is hit in the end.