Ali Candan, a Turkish diplomat in Kosovo, who is also an undercover agent for KGT ("Kamu Güvenliği Teşkilatı", or "Public Security Organization") is ordered by his superior, Aslan "Amca" Akbey to infiltrate and destroy the Turkish mafia.
When Candan returns to Turkey, he secretly undergoes several surgeries to change his face and his voice, and takes upon the name "Polat Alemdar". Alemdar is placed by Aslan "Amca" Akbey in Duran "Emmi" Şatıroğlu's side, who used to be a respected mobster in the past. Şatıroğlu now owns a traditional Turkish café which is often guested by mafia leaders, and he is also informed of Alemdar's task to act as his aggresive nephew who aims to become a Mafia leader.
As his journey begins, Alemdar has to keep his secrets from everybody, including his family and his love, Elif Eylül while working to get on top of the great Mafia "baronate" and destroy it.