"Big Brother" is set to premiere this week. For Season 27 of the hit reality competition series, the official theme will be "Big Brother: A Summer of Mystery," CBS confirmed Wednesday, July 2.

Big Brother has unveiled a new cast of scheming players, and teased the mysterious returning alum. We have a theory!

Big Brother season 27 houseguests include a dungeon master, a college sports podcaster, a bridal consultant, and a professional bull rider.