I'm glad someone else mentioned it. First thing I thought of when reading this was "Didn't this party make any friends?"
If Ragu had just left the dead corpses in the dragon's lair, someone could come across them. Assuming that the party had some allies, there really isn't anything that mind bending about those allies going to find out what happened to their friends. That is why the good guys win, they help each other.
I don't think it takes a miracle, wish, or anything of the sort to bring these guys back. All it takes is someone who is willing to investigate what happened, someone who has a reason to worry when the party disappears like that.
How tough it is to scry on the missing priest, see a decaying corpse, and figure out what happened?