CBS has launched Season 27 of its long-running reality TV series "Big Brother," premiering on July 10, 2025, at 8 p.m. ET. The season is officially titled "Big Brother: A Summer of Mystery" and features a new thematic setting called "Hotel Mystère," an enigmatic and luxurious version of the traditional "Big Brother" house. The cast includes 16 new houseguests with diverse backgrounds such as a dungeon master, a professional bull rider, an aura painter, an attorney, and an AI consultant from Sarasota. A notable element of the season is the inclusion of a secret 17th mystery houseguest whose identity remains undisclosed. The season also introduces new twists including a masked visitor and a secret accomplice, alongside a new iteration of the BB AI Arena. New episodes are available to watch and stream following the premiere.