This is a retelling of the myth of Jason and the Argonauts. They brave adventures to sail to Colchis in the Black Sea (the first Greek fleet to enter the Black Sea through the eponymous clashing rocks) to recapture the famous Golden Fleece. But they need the help of witch Medea who falls in love with Jason and requires him to mary her as the price of her help. But part of her help involves the murder of her brother. Later when Jason is safely back home Medea poisons his uncle the King which revolts the people and means that Jason and Medea need to flee. Finally in exile Medea kills two of Jason's children and leaves him.
Which is perhaps the most distressing story in the whole of the Greek pantheon (although the Oresteiad) is perhaps as dark.
It was simply told by Serraillier. He added very little although there were little touches to add reality to such things as Medea's love and the way ordinary people reacted to the tale. But it is still mostly a bald myth.