On Monday's upcoming Halloween episode of NBC's THE SING OFF, the seven remaining groups celebrate the Day of the Dead in with a big opening production number. Included in the Halloween medley are "This is Halloween", "Werewolves in London", and "Ghostbusters".

NBC's THE SING OFF is the unique competition series that sings a different tune and is hosted by multi-platinum recording artist Nick Lachey, returns for season three this fall in a weekly format with two-hour episodes.

The show scours the country in search of the best a capella groups, ranging in size and age. This year the competition has expanded to the 16 very best groups who will perform popular songs in a weekly competition that will culminate with a live finale revealing the grand-prize winner. The groups will be competing for America's vote and a chance to walk away with the ultimate prize -- a Sony Music recording contract and a $200,000 cash prize.

There's no lip-synching, back-up bands or safety net. One group will be eliminated each week during this one-of-a-kind battle of voices that will lead up to a live finale -- where viewers will decide the winner.

Celebrity judges who will critique the singing groups, using their musical expertise, are Ben Folds (Ben Folds Five), Shawn Stockman (Boyz II Men) and Sara Bareilles ("Love Song" and "King of Anything").

To watch the spooky opening number to next week's show, click below!