This is the third mission of a small questline to complete one request of the Kings of Sparta.

At the end of The Contender, it appears Alkibiades has been poisoned at the banquet he was at. Head to the Leonidaion, which is not far from the Temple of Zeus in Olympus.

Upon arriving at the Leonidaion, head to the very back room on the left. There's evidence of poisoning, and time to investigate.

Head back to the entrance and enter the room on the right; this is the room where the investigation will take place. Look for the following clues:

The pitcher and cups on the chest to the left

The food on the center table

The note on the table in the small supply closet behind the center table

Once all the clues have been found, it's time to head to the merchant who sold the food to the hosts. He's near the Leonidaion in the Sanctuary of Olympia. In the long temple, head to the left to find him in the back room.

A conversation with him will begin upon entering the room. Gather information about an antidote and decide on whether or not to kill him for his crimes. When the conversation ends, a guard will stand outside the room; escape via the window to go unnoticed.

Now it's time to get the antidote; it's being held in Fort Korobios. It is northeast of Olympus. Call Ikaros to mark the target and all enemies, and meditate until night time.

This is a difficult mission to complete with few kills as the antidote is in a room in the middle of the fort. Stick to the bushes and perform stealth kills as often as possible; just don't stealth kill guards from bushes with torches in their hands. Sneak down to the room and loot the chest the antidote is in and escape the fort.

Return to Alkibiades in the Sanctuary of Olympia. Alkibiades is under a tent outside on the western side of the building. There is a chance to kill Kallias, a member of the Cult of Kosmos on the way back to him. After a short cutscene upon arriving at the tent, the mission will be complete.