Once upon a time, there was a haunted castle. Except, it wasn't so haunted anymore. Once it had been proud haunted castle. It (once) had every type of ghoul and nasty imaginable. It had were beasts of various species permanently in their hybrid forms. It had zombies. Vampires. Witches. One of Frankenstein's monsters. Mummies. Ghosts. Swamp-man. And so many more . . .
But... times had been tough.
The vampires had all been staked (commoners were no longer considered free blood banks apparently), the witches all burned (parents objected to their children being magically turned into cookies, go figure), the mummies had been unwrapped for their jewelry then ground up and sold on the black market. The were beasts had all been stabbed in the palms with silver needles and told their christian name three times (strangely this text book ability to cure werewolves never really came out anymore). The ghosts had all moved onto the afterlife. The zombies had rotted away, and the skeletons had been torn apart by dogs. And the swamp man's lair had become too polluted to sustain it in the caverns beneath the castle. The various other horrors had met similar fates. Even the beautiful living suits of armor had been dismantled and sold to museums during the day.
A village, and then a town had sprung up around the old castle, and had entered the modern era, the castle itself little more than a tourist attraction, and not a very popular one at that. The castle itself, was not amused at all at its fate. It had once been a proud and proper haunted castle... even a haunted woodshed would snicker at its plight now. But... the haunted castle had one sliver of hope left to regain its lost pride.
A full moon on all hollows' eve was coming... and this night... the haunted castle would use what power it had left to 'bring back' what it had lost. Children in costumes. Rowdy teenagers. Curious adults. The castle would use the remnants of its power to draw them here, and use it the last of its magic to distort time and space, so the night would last around the castle for the deed to be done, and those drawn would not think to simply leave. Of course there were those annoying cell phones, but good magically residue stone would provide enough inference.
And once inside, they would be drawn into their new roles to make the castle the figure of super natural fear and luster it once was. Children by their costumes, others by their faults or desires, both hidden or otherwise... It knew the myths and legends had changed over the years, but the old castle wasn't that allergic to change. Once inside, those inside would find various objects, curses, and other things that would change them into the classical and beloved (and feared) creatures of horror and ghost stories.
The sun was beginning to set, and the (empty) haunted castle was determined, and around the town, tourists, visitors, and what not, would all be unconsciously drawn to the castle to become its new residents.