After a corpse is found in the Bosphorus, two detectives Kemal and Settar, who have completely opposite characters, begin to investigate the mystery behind the incident.

Detectives, who encounter the symbol of "Alef" in the house where the murder is committed, begin to investigate the symbol. The voice recording left by the killer directs them to an Islamic History expert named Yasar.

While eyewitnesses at the marina lead detectives to an old cemetery, Kemal catches an important clue in the sound recording of the killer.

The identity of the person who brought the box sent by the killer is found, while the histories of Settar and Kemal are gradually revealed.

As ropes begin to stretch between Kemal and Settar, Settar pursues dangerous information.

Kemal identifies the next victim's identity and takes what she learned to an old crime scene.

Kemal discovers that Settar hides something from him and goes over this. Then Kemal realizes Settar isn't only one that hides something from him.