Jason shows up in his hometown of Iolcus to demand that his wicked uncle Pelias return the throne to him, the rightful heir. Pelias stole the throne from Jason's father, Aeson. King Pelias says, “Sure, no problemo. But first, you have to sail to the distant land of Colchis and fetch the Golden Fleece."
Read this part carefully,
Hope this helps you find your answer!