Ever been to see The Phantom of the Opera? If so, you'll know exactly what we're talking about when we say that we imagine this poem taking place in a big old cavern of a theater, filled with cobwebs and echoes and ghostly sounds. Things definitely go bump in the night here. It's not that it's depressing, really – just sort of gloomy and exciting and spine tingling, like a good horror movie. That haunted criminal (lines 33-40) would find plenty of gloomy little crannies to slink into. There might be bright lights on the stage, and happy music here and there (the mood is pretty cheerful in parts of this poem), but there's always that spooky feeling in the background.