Head guard Hamza and his team conduct a headcount every morning at the prison. One day, during a routine check, they find one or two bodies in each cell they enter. There are no signs of beating, injury, or strangulation on the bodies of the ten prisoners found dead in eight cells. The other prisoners in the cells also make no statement about the incident. Selin Korkmaz from the intelligence agency and Chief Inspector Erol Haktan from the homicide department are assigned to investigate the incident. The two begin their investigation by quarantining the prison and questioning everyone inside. As Erol and Selin meticulously investigate every detail to solve the mystery of the murders, they uncover shocking truths with each "lock" they open.

When a serial killer goes after former convicted pedophiles, it is up to Police Commissioner Abbas and his Chief Celal to stop the killings.

Ozgur is a young woman who is the daughter of a refugee family fled to France. She is born and raised in Paris. After her father Huseyin's death, she comes to Istanbul to fulfill Huseyin's last wish. He wanted to be buried in his own country. But because of September 12 military coup d'etat period, Huseyin is no more a Turkish citizen. So this happens to be a great obstacle for Ozgur. This will force Ozgur to a journey both in Istanbul and herself. In this journey Ozgur will meet with her father's and mother's relatives who are completely different people. Most importantly she will meet with Ferhat who will deeply effect her. This journey will become a confrontation with themselves and 2011's Turkey for Ozgur and Ferhat.