This was a whole lot of fun and full of interesting ideas. As you can guess from the title it revolves around what happens when magic disappears from the world and those with, if you like, power become powerless. It was interesting to see how quickly those now bereft of their magical abilities become the 'underclass', how quickly those that once needed them and their skills turn on them.
What caught me most was what happened with those classed as 'Moon Children'. Those with magic got there power from a moon whereas Moon Children were 'blocked' by it and kept in a state of childlike ability. Unable to think well, communicate etc they are seen as low and only capable of menial tasks. When the moon is destroyed and magic fails then the 'block' fails and they reach their true ability.
The ending of the story was not what I was expecting but was one to make you think