July 10 marks the highly anticipated 90‑minute premiere of Big Brother 27, kicking off at 8 pm ET/PT, with a second 90‑minute episode airing Sunday, July 13. After that, episodes will air Wednesdays (now expanded to 90 minutes), Thursdays (eviction nights), and Sundays—as usual—while fans will also get behind‑the‑scenes content in the new companion show Big Brother: Unlocked, airing every other Friday starting July 25 .

Big Brother 27

Julie Chen Moonves, still the iconic host since Season 1 in 2000, has been dropping fun teasers across social media, even posting interior shots of the house and multiple pics with skeleton keys and magnifying glasses, hinting at a playful, mystery‑filled theme that feels a bit like Clue meets murder‑mystery weekend .

CBS has officially revealed that the season’s theme is Hotel Mystère: a hotel‑styled murder‑mystery house packed with secret passageways, hidden rooms, and clever design details . With rooms like a 75-key-box reception area, a 1920s train‑style bunk room, a poison bar/lounge, a wine cellar, a rooftop garden kitchen, and even a boxing‑ring gym, this season visually screams “investigate me” .

That wall of 48 ornate keys in the promo art isn’t just aesthetic—it symbolizes the strategic layers and locked secrets within the house. Julie teased that “the keys to unlocking unexpected mysteries … are right in front of you,” and producers promised it will be “the most unexpected season of Big Brother yet” .

Gameplay-wise, the much‑loved three‑nominee format returns from Season 26’s AI Arena twist, ramping up suspense on eviction nights. Julie even confirmed it’s back based on how well it played last year .

The premiere will shake things up more than usual: fans are promised a masked visitor, a secret accomplice. Most explosive is a mystery houseguest whose identity will remain concealed. It could be someone very polarizing. Julie said she was “shocked” when producers told her who it was. Viewers will have strong reactions “in both directions” . Rumors swirl about possible returning villains or surprise public figures. CBS emphasizes it’s all a secret for now .

The Hotel Mystère house is packed with coded décor. Think detective‑style gameplay: giant chess pieces, curios in the attic, snake‑patterned venom lounge, and even a “Poison Bar”—metaphorical, hopefully! The idea is that contestants will need sharp observation and puzzle‑solving skills to gain an advantage .

As for casting, CBS confirms an all‑new group of houseguests, no returning players, though the mystery guest is the only possible exception . Julie and production teased that the casting stayed open late into spring, targeting bold personalities ready for drama .

Fan theories are already in full swing: some suspect murder‑mystery puzzle elements, locked rooms accessible via keys, spy mechanics where alliances or powers are “unlocked,” and maybe even someone from outside reality TV sneaking in .

Big Brother 27 premieres July 10, debuting Hotel Mystère—a stylized, secret‑laden twist on the classic format. With a masked visitor, a secret accomplice, a mystery houseguest, three nominees, and a setting that feels primed for decoding, Julie Chen Moonves is inviting us all to play Sherlock this summer. The question is: who’s behind the mask? Which key unlocks the season? I’m already ready to start sleuthing—hope you are too!

Photo Credit: @juliechenmoonves Instagram