You will come upon Herodotos and two men arguing with each other. They both say that the other stole from them. To protect the Olympic Truce, you decide to investigate and find out what really happened. Go to the treasuries on the north side of the Sanctuary of Olympia.
You’ll talk to the guards outside, who will tell you that he fell asleep and did not see the robbers, so you need to investigate. Once you’ve done that, the note will let you know that the thief went to the ruins of the House of Oinomaos, to the northeast of town.
The thieves are together inside. It turns out they are the son and daughter of the two men who were arguing, and they wanted to take the money and run away together. However, their fathers will see you all and tell you to kill them both. So, you can either kill the parents, or the children. The loot is the same either way.