The life of Osman Bey, the son of Ertuğrul and the founder of the Ottoman Empire, as he established and controlled it, facing internal and external struggles against Byzantium and the Mongol Ilkhanate.
Osman, nephew of Dündar Bey, navigates a treacherous path as he confronts the machinations of Selçuk Sançak Bey Alişar and the ruthless Sofia of Kulucahisar, who plots against the Kayı tribe, while also battling external threats from the Mongols, culminating in the conquest of Kulucahisar and Osman's marriage to Bala.
Osman faces new challenges as he becomes the Sardar after his father's death, marries Malhun Hatun, and battles the Byzantines and Mongol Governor Geyhatu, ultimately leading to the Battle of Domaniç and the execution of his treacherous uncle Dündar.
Osman Bey faces challenges from the Byzantine Emperor, a Mongol Governor, and a treacherous uncle, while also navigating alliances, betrayals, and the death of his father, ultimately leading to the Battle of Domaniç and the death of Togay.
Osman faces Byzantine plots, including Kantakuzenos's assassination attempt and the framing of Öktem Bey and his daughter Alcicek, which Osman ultimately foils, while Alcicek and Aktemur fall in love.
Osman Bey continues his quest for Bursa, faces challenges from Yakup Bey who declares himself Sultan, and navigates conflicts with the Ilkhanate and Byzantine forces, including the kidnapping of princess Maria.
Sofia, who was thought dead, returns and joins forces with Commander Lucas, raising Halime, Osman and Bala's daughter, as her niece and training her against her parents, while the Kayi tribe faces threats from the Mongols and internal tensions.