"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.

The cast of "Big Brother" Season 27 has been revealed — with one "Mystery Player" set to make a surprise entrance.

Big Brother follows a group of people living together in a house outfitted with more than 100 cameras and 100 microphones, recording their every move 24 hours a day. Each week, someone will be voted out of the house, with the last remaining Houseguest receiving the grand prize of $750,000.