S1·E27 The Day of Victory - Season Finale

The 'dark knights' injure Osman very badly and everyone believes he is dead, however, Osman is actually alive but he only tells Gündüz, Bala and Selcan. Taking advantage, Osman conquers Kulucahisar Castle and kills Sofia in the process. Aygül, who is mentally ill, attempts to kill Hazal because she killed her mother, however, the arrow accidentally kills Burçin instead.