Having wrestled and defeated Achelous, god of the Acheloos river, Heracles passes through Calydon, discovers a wild centaur named Nessus attempting to kidnap Princess Deianira, sister of Meleager, as he was ferrying her across the river Euenos. Heracles shot the centaur with a poisoned arrow. As he lay dying, Nessus persuaded Deianira to take a sample of his blood, telling her that a potion of it mixed with olive oil would "excite the love of her husband". Heracles returns her to Oeneus, King of Calydon, who conscents to her marrying the hero.