Geronimo Stilton #50: This Hotel is Haunted!

My good friend Hercule Poirat and I were called to investigate mysterious events in the famouse Grand Hotel in New Mouse City. There was a ghost haunting the hotel and scaring guests! It was wearing armor and carrying a ball and chain. I know that ghosts don't exist but this was pretty spooky. Would Poirat and I be able to solve this spine-tingling mystery?