Neverending Masquerade

It began the same way for each of you. An invitation, gilded letters guiding you to the ancient manse. A masquerade ball, for one and for all, it promised to be the party of the century. Of course you simply had to accept.
An ebony carriage pulled by white stallions awaited you at the gates to take you the two mile journey up the path to the main house. You were loaded in with some other late arrivals, and had the opportunity to get to know each other.
What you saw as you took your slow plod up the dirt path through the woods was wonderful: amid the trees, streamers of golden chains woven into an intricate web, glittering with precious jewels. Elaborate carvings on the side of every tree, telling a story that you could not quite understand, but nevertheless brought a pang of sorrow to your heart. The sounds of owls hooting filled the air as you approached the main house just as the sun was setting directly behind it, casting a ruddy hue across the grounds.
Once you arrived, you were led to a grand ballroom filled with lords and ladies from all over, realms exotic and mundane. Each and every one of them wearing a mask ranging from simple, to full headpiece. There was even one lord who had the head of a tiger!
As you were the last to arrive, the party was already in full swing. Attendees making merry, snacking on the copious amounts of food available. It was five hours before you noticed anything was amiss, well into the night. You didn't realize it at first, but the number of attendees thinned out as the night went on. Not too unusual, people leave parties all the time, you thought. And yet, there were no carriages out front to take them back down the drive.
As the realization dawned upon you, you chanced to see one of your companions from the cart getting dragged off down a hallway by some... thing. Against your better judgement, you followed and arrived just in time to see them disemboweled, viscera painting the walls with a sickening thud. Then, everything went dark.
You exited the carriage, and looked in horror at your companion who had, by your estimation, had just been gutted and killed. Who now stood before you whole, and intact...and just as horrified. Something's horribly wrong here, and you need to figure it out if you're ever to make it away from this party alive.
Areas of Note: Grand Ballroom, Kitchens, Scullery, Bedroom Wings, The Gilded Woods, Family Crypt
Goal: Figure out what the hell is going on and make it through the masquerade alive.