Cavalli’s Il Giasone isn’t a work one sees performed often. It’s a peculiar beast. It’s about Jason and Medea and the Golden Fleece but has few of the elements of the version of the story that everone knows and everybody from Charpentier to Reimann has made into an opera. In Cavalli’s version Giasone has got Isifile, a princess of Lemnos, pregnant with twins and then gone off after the Golden Fleece. In Colchis he spends his time in bed with a mysterious local beauty, much to the disgust of Ercole who thinks he’s gone soft. Eventually Giasone works out that his squeeze is Medea and with her help defeats some monsters and grabs the fleece.