The Argonauts were a number of heroes who participated in the Argonautic Expedition, setting sail for the mythical land of Colchis under the command of their leader Jason, in order to find the legendary Golden Fleece.
The story unravels years before the Trojan War, when King Cretheus of Iolcus died and Pelias usurped the throne from his half-brother Aeson. However, he was told of a prophecy, according to which a descendant of Aeolus would seek revenge for his acts. Killing every possible descendant of Aeolus, Pelias spared his half-brother and incarcerated him. Aeson married Alcimede, who gave birth to Jason; faking her newborn's death to trick Pelias, Alcimede managed to hide her son in an area near Mount Pelion, where the centaur Chiron raised and nurtured him.
As a young man, Jason returned to Iolcus under Hera's command. He attended a sacrifice to Poseidon where Pelias and other kings were present, and his uncle recognised him. Unable to kill him in front of so many guests, Pelias told him to fetch the Golden Fleece which was hanging from a tree somewhere in the far-away land of Colchis. This venture sounded impossible as the Fleece was guarded by a never-sleeping dragon. In fact, Pelias was so certain the mission would fail that he swore he would give up the throne if Jason returned with the Golden Fleece.