How does orpheus lost eurydice the second time summary?

Orpheus went to the Underworld and charmed Persephone (the wife of Hades) with his singing and she persuaded Hades to let Orpheus take Eurydice back to the world of the living. Hades however wasn't so amenable and he place a condition on the deal that 'Orpheus must not look back until he has succeeded in returning the both of them to the light of day.' Well, as Eurydice was only freshly dead the snake bite on her foot was still sore and she lagged behind. As Orpheus was approaching the exit the worry that Eurydice was not behind finally got to him and he turned and looked. At that the demons of hell dragged her back down.