As Tom rehearses his wedding vows in the forest on the eve of his planned wedding to Victoria, he accidentally puts the ring on the bone finger of a dead girl that is you

The corpse bride (Du) was murdered by her lover when she wanted to run away with him and has been waiting for her heart mate ever since. She insists that she is now Tom's legal wife and takes him with her to the underworld

Tom: "Where am I?!W-Why am I here?!"