Well this book was weird! A book about Merlin opens with Jason, of Golden Fleece fame, attempting suicide through grief for his two dead sons, killed by their mother, Medea. Huh?
Flash forward 700 years and it turns out that Merlin was one of the Argonauts and that he's discovered that Medea did not kill Jason's sons afterall - in fact they are alive in the present, hundreds of years after they should be dead even if they had lived to old age.
Jason isn't dead, either - he's half-dead in the bottom of a demon haunted lake, protected and kept from fully dying by the Spirit of his ship, the Argo. Merlin brings both from the bottom of the lake and restores them to full life. A new quest begins with new Argonauts, a renewed Argo carrying a forest Goddess rather than Hera and only Jason and Merlin remaining from the quest for the fleece. This time Jason is searching for his sons but the voyage of the Argo proves as inordinately long and difficult as the previous ones and the story is not over when the end of the book arrives - indeed there are two more volumes following.
The story is set mainly in the lands and time of the Pagan Celts and I've never come across a more convincing evocation of them; it's not a suprise though - rather to be expected from the author of the Mythago books - and it transpires that there is a gigantic Mythago Wood in Britain, known to one of the New Argonauts, Urtha, whose home borders it, as Ghostland.
Merlin is an intriguing character with an intriguing background. His mastery of the natural magic in the world comes from charms written on his bones and his tale (he tells it himself in the first person) is a strange one. I'm very keen to finish it.