Muhteşem Yüzyıl: Kösem

Ahmed, son of Sultan Mehmed III and Handan Sultan, becomes the ruler of the Ottoman Empire after the execution of his older brother Mahmud, and the unexpected loss of his father, Sultan Mehmed III. One day, his grandmother, Safiye Sultan, gives him a portrait of a young girl named Anastasia (also referred to as Nasya) who lives in the island of Tinos (modern day Greece) with her family, holding a lamb in her arms. As he takes a liking to the painting, she personally orders for the girl to be brought to Topkapi Palace. After being captured and brought to the palace, Cennet Hatun, begins to lecture Anastasia on palace etiquette and courtesy. Though Anastasia swore she would return to her homeland at all costs. While wandering the palace, she discovers a mysterious passageway leading to a secret garden, where she first meets Ahmed. However, Ahmed introduces himself with a different name and soon Anastasia begins to have feelings for him. The other harem concubines, envious of Anastasia's beauty, begin telling false tales to Anastasia, making her believe the sultan eats young girls' hearts. As Anastasia is later taken to the sultan, she then learns of his true identity and reason for her arrival at the palace.

Not long after, Ahmed becomes ill and is thought to be poisoned. However, Bülbül Ağa finds out that Ahmed's malady isn't poison, but pox. Riots take place when the locals discover what is happening. Hope emerges at the face of Ahmed's concubine Rasha, who is found to be pregnant but Halime Sultan has the girl attacked by bandits while being sent to safety. Safiye, fearing the end of the three century old Ottoman dynasty, encourages the rest of the family to leave the palace with her. Anastasia, willing to stay with Ahmed, is reluctant. She stands in front of the rebels and is shot, though the bullet lands on her Ta'wiz. Later, Anastasia visits a sorceress, who gives her a cure to Ahmed's pox. In return, Anastasia is told that she will walk a road filled with blood, she will see all the people she loves die before her eyes. Everything turns normal and Anastasia's name is then changed to Kösem, which means "sheep leading the herd", indicating her future leadership and intelligence. She also converts to Islam. Safiye asks Kösem to convince Ahmed to let her remain in the palace, but Kösem refuses, saying that she should have stood by Ahmed when he needed them. This marks the beginning of Kösem and Safiye's animosity.

When Kösem's father Enzo is kidnapped and taken hostage by her guards, Safiye blackmails Kösem into telling the Sultan about Handan's crime and convinces him to keep her in Topkapi. Ahmed later banishes his mother to the Old Palace (also known as Eski Saray and the Palace of Tears). Safiye, however, does not keep her promise and kills Enzo. Kösem is enraged and vows for revenge. Kösem later learns of Safiye's secret from Cennet and personally gives Safiye a warning. The next morning, all the harem is alarmed at Safiye's departure. Rasha, renamed Mahfiruze, gives birth to a son named Osman. Kösem finds out that she is pregnant. Ahmed hands Kösem the crown of Hürrem Sultan, showing his love and respect for her. After this, Kösem blurts out Safiye's secret to Ahmed, which infuriates him and later becomes distant from her. Handan returns to the palace and Kösem later bears a son named Mehmed. After learning that Fahriye has died, Safiye is left heartbroken and vows to take down Ahmed from the throne. Ahmed leaves for his military campaign against Safavid Persia, while Safiye orders Ahmed's assassination; as she buys loyalties of the pashas and the janissaries. Many were killed including Mahfiruze Sultan. Kösem escapes execution with the help of Zülfikar and Bülbül Ağa. Ahmed arrives in perfect timing, having survived the murder attempt thanks to Dervish. He incarcerates Safiye in the Maiden's Tower and strips her off all her power. Then, he decides as a ruler to execute his brother in order to secure his crown, but later spares Mustafa, and instead has him put in confinement. Kösem, apart from being allowed to raise Osman herself, also takes Meleki, a poor young girl whom she has befriended and was left motherless due to the events of the coup, under her wing.

Hümaşah Sultan, Safiye's eldest daughter, arrives from Egypt. Not long after, Kösem is told by Mehmed Giray about the truth of Dervish and his role in the assassination of Sultan Mehmed III. Meanwhile, due to Halime, the truth of Handan and Dervish's feelings for one another is exposed, making Handan vulnerable. The secret of Dervish's involvement in Sultan Mehmed III's death is revealed to Ahmed, who kills Dervish himself. Handan soon commits suicide, fearing that her secret has been told to her son. After Handan's death, Hümaşah is given the leadership of the harem. During this time, Ahmed prepares to build a mosque opposite Hagia Sophia. Ahmed orders the release of Safiye from the Maiden's Tower, due to her aid in rescuing Kösem from the bandits. Hümaşah later resigns from her role, due to Kösem's intrigues. Later, the former is informed by Bülbül that her long lost brother, is revealed to be Iskander and is the lost prince of the Ottoman dynasty. Safiye and Hümaşah both conceal this truth for over eleven years, during which time Kösem consolidates her power and bears seven more children. Zülfikar and Hümaşah marry, and Iskender assumes the post of Hasodabaşı (chamberlain of the Sultan). Ahmed, has also sired a son, Bayezid, from a third concubine, Gülbahar. On the auspicious occasion of Eid ul Fitr, Ahmed decides to release Mustafa, who unbeknownst to everyone has become mentally unstable over time. The Sultan Ahmed Mosque has been completed. Ahmed, along with his sons and brother Mustafa, say their Friday prayer at the mosque. Once again, Safiye attempts to assassinate Ahmed by poisoning him in order to clear the path for her own prince through a concubine. She succeeds and Ahmed, who is already suffering from stomach problems, is eventually told he has less than a fortnight to live. Kösem meanwhile has the girl killed, only to find out that she was her sister.

In a moment of haste, Hümaşah informs Zülfikar about Iskender's secret, and he in return informs Kösem. Kösem, fearing for her children's fate after her husband's death, convinces Ahmed to order Iskander's execution. As Ahmed learns that his disease is progressing, he asks that he be legally married to Kösem before he dies. A few days after, Ahmed passes away due to abdominal pain. Kösem then aids Şehzade Mustafa in gaining the crown, however Halime, along with her daughter Dilruba Sultan turn against her; banishing her to the Old Palace. In the meantime, Iskender, having been spared by Zülfikar reunites with his mother and they plot to seize power and exact revenge. Realizing her mistake, Kösem plans a coup d'état to dethrone Sultan Mustafa and replace him with her stepson Şehzade Osman. Kösem uses Mustafa's weak mental state in order to justify her actions. Halime, seeing Kösem's sons as a threat to her authority, orders them executed, but with the unexpected help of Bülbül and Hümaşah, Kösem arrives just in time to save them, and then orders the janissaries to throw Mustafa in prison, and send Halime to the Old Palace. Osman ascends to the throne as Osman II, but he refuses to end Kösem's exile at the Old Palace, due to her role in Mustafa's ascension and three years later orders the execution of her eldest son Mehmed, who he believed, due to Safiye and his tutor's intrigues, the janissaries saw as a candidate for the throne.

Distraught, Kösem decides to dethrone Osman, while at the same time she repays Safiye by collaborating with Zülfikar to apparently kill Iskender. This event causes Safiye to commit suicide; dying, she admits her defeat to Kösem and gifts her with Hürrem Sultan's emerald ring. Eventually Osman's plans to replace the janissaries with a more loyal army proved to be the primary motive to his abashment, masterminded by Davud and during which Cennet and Zülfikar are killed, with subsequent incarceration and strangulation, thus enabling Mustafa's second reign to begin. Hümaşah leaves the capital forever. Kösem, having reconciled with her stepson but failed to save him, is immensely anguished by his loss and decides to annihilate all her rivals. Thus, she orders those who holds allegiance, to dispatch Davud, Dilruba and Halime, then imprison Mustafa again after viewing his psychologically disturbed condition not a threat to her rule. She then prepares to enthrone her eldest living son Murad to the Ottoman throne, thus inheriting the position of Valide Sultan, declaring herself the official regent to the crown and gaining her prestige as the most formidable, influential, and powerful sultana in Ottoman history.

Kösem has been the all-powerful Valide Sultan and regent to her son Sultan Murad IV for nearly a decade, when the military unrest causes the latter to deprive her of her authority and the two clash. With the control of the state fully in his hands, Murad sets his plans of restoring the empire to the times of prosperity and conquest and checking corruption in motion. At the same time, the Hungarian princess Farya Bethlen seeks refuge at the Ottoman court and the instant attraction between her and the Sultan causes reactions from Kösem and Murad's wife, Ayşe Sultan. A strain is also put on Murad's relationship with his sister Gevherhan after the execution of her husband, as well as in hers with their mother, when she eventually opts for love instead of power games. Their half-brother and Crown Prince, Bayezid, though loyal himself to the sultan, is drawn in conflict too, due to the ambitions of his mother, Gülbahar, who has been long obscured by Kösem; all the while the other princes' and infidels' agendas remain unknown and anti-Ottoman sentiments and plans resurface in the West.

The second season also introduces the reign of Sultan Ibrahim, the clash between Kösem and her daughter-in-law, Turhan for the title of Vailde Sultan, concluding the series with Kösem's assassination.