I had no idea when I reserved a copy of Joseph Delaney's The Ghost Prison that it was in fact a short story of around 100 half size pages: so in essence, a 50 page book. However, as far as modern short stories go it was an interesting little diversion, but with hardly enough content to fully flesh out the idea. That said it had little references to Delaney's The Wardstone Chronicles Series which begins with The Spook's Apprentice and so this should interest Delaney fans.
The basic premise is that the reader is introduced to a new boy, called to become a prison keeper at a prison haunted by ghosts. Part of the duty of the jailers is to make sure ghosts are kept in line, but also to feed the one mysterious prisoner hidden in the Witch's Well. Of course our protagonist is told never to go down to the Well, but one day no one else is available and so it becomes his duty.
If you want a quick easy read for a brief distraction this is certainly the short story for you. I personally would have liked something that was more developed but it works to provide an interesting story with a puzzling little twist at the end.