To begin this quest, speak with Sokrates, who can be found at the residence of Perikles. He has a plan to besmerch the reputation of Kleon. Accept the plan to uncover evidence of his association with the cult. Killing him immediately will deprive you of the evidence. You must go to the Akropolis at the centre of Greater Athens and begin your search at the Statue of Athena.
When you reach the statue, use Ikaros to identify a more precise location where you can search; the heavily guarded building beside the statue. Now that you have identified the building where you should be searching for clues, approach it from the south side to enter unnoticed. You will find a chest in the back garden, which has recently been dug up. Go inside the house to find the shovel that was used to dig the chest up. You will also find a note in the front room of the house, leading you on to a clue of where you can find the key; with a commander named Phaelos.
You will find him patrolling around the front side of the Parthenon. Climb atop it and assassinate Phaelos from above. You can then loot the key from his body and return to the locked chest. When you have the proof, meet Sokrates at the Pynx to the south west and join him in making the speech. Choose the following speech options for the best outcome:
- “Of course I’m not!”
- “People with expertise know better.”
- “I’d find someone new.”
When the speech is over, a brief cut scene with Sokrates will mark the end of the quest.