What happened on Big Brother? Season premiere recap and mystery houseguest revealed

The Big Brother house reopened its doors for season 27 with a murder-mystery twist, a dramatic host disappearance, and the surprise return of a winner. Host Julie Chen Moonves kicked off the summer with a two-hour premiere full of theatrics, high-stakes competitions, and the introduction of 16 new houseguests—plus one mystery guest.

The season’s Hotel Mystère theme was immediately established as a cryptic countdown clock loomed over the house, eventually triggering a blackout that saw Julie vanish, leaving only a single high heel behind. A masked Mastermind appeared on-screen, teasing a season of deception, secret accomplices, and a mystery houseguest whose identity would soon rock the competition.

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Big Brother season 27 premiere night highlights

The season opened with Julie introducing the elaborate new house design filled with mysterious keys and hidden clues. After meeting the new cast, a dramatic countdown timer triggered the first twist of the season. As Julie warned houseguests to "expect the unexpected," the lights cut out, and the Head of Household relic vanished, along with the host herself.

A red-masked figure called The Mastermind appeared on screen, announcing that the game couldn't continue without finding both Julie and the missing relic. The houseguests were divided into teams for two crucial competitions that would set the tone for the season.

The episode introduced the 16 new contestants in two groups. The first team was The Rescue Mission, in which eight players raced to find Julie, solving puzzles to unlock doors. Zach emerged victorious, winning $10,000 and securing the first power of the season.

The second team was The Head of Household (HOH) Relic Hunt, which had the remaining eight contestants search for the missing HOH relic. Jimmy Heagerty triumphed, earning the right to choose four players for the first Head of Household competition.

Jimmy selected himself, Adrian, Ashley, and Vince for the inaugural HOH challenge, a balancing act where contestants had to stabilize weighted "cores" on mechanical arms. Vince’s steady hand won out, making him the first Head of Household of season 27.

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The teams and houseguests

The first team consisted of:

• Kelley Jorgensen
• Zach Cornell
• Ashley Hollis
• Rylie Jeffries
• Amy Bingham
• Adrian Rocha
• Lauren Domingue
• Keanu Soto

The second team consisted of:

• Katherine Woodman
• Vince Panaro
• Mickey Lee
• Jimmy Heagerty
• Morgan Pope
• Isaiah Frederich (Zae)
• Cliffton Williams (Will)
• Ava Pearl

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The Big Brother mystery houseguest revealed

Just as the houseguests settled in, the Mastermind returned with a bombshell: Rachel Reilly, the iconic winner of Big Brother season 13, entered the game as a surprise 17th houseguest. But there was a twist, Rachel wasn’t the only wild card in play.

The Mastermind revealed that one of the original 16 contestants is his secret accomplice. If the house fails to uncover the mole, that player will remain in the game as an official 17th competitor. If exposed, they’ll be ejected immediately. Rachel, meanwhile, is here to stay.

With Vince as HOH, the first nominations loom, and the house is already buzzing with alliances, rivalries, and speculation about the hidden accomplice. The AI Arena returns as the BB Blockbuster, offering players a chance to win game-changing advantages.

This season adds 90-minute Wednesday episodes and a new aftershow, Big Brother: Unlocked, featuring past houseguests breaking down gameplay. Fans can watch the action unfold 24/7 starting July 14, though the flashback feature remains scrapped.

The premiere set the stage for a season full of deception, drama, and high-stakes gameplay. With Rachel Reilly back in the mix and a potential mole lurking, Big Brother 27 is shaping up to be one of the wildest summers yet.

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Big Brother airs Sundays, Wednesdays, and Thursdays on CBS, with live feeds available on Paramount+.