[Warning: The following contains MAJOR spoilers for the premiere of Big Brother Season 27.]

Who turned out the lights?!

Soon after the first four houseguests entered the house, the camera zoomed in on a mysterious digital clock, which was counting down from ten as the contestants poured in. It wasn’t until Julie Chen Moonves came on the screen in the living room during the final minute that any of the contestants noticed something was awry. Cue: a sudden blackout and a missing host.

After the 16 houseguests entered the house during the Big Brother Season 27 premiere, they were instantly hit with Big Brother: A Summer of Mystery‘s first major twist: the shocking disappearance of Julie Chen Moonves. Or at least, that’s what contestants were led to believe as they watched the host’s warning to “expect the unexpected” get cut short by a sudden loss of power. When the lights turned back on, Moonves was gone—along with the season’s first HoH relic.

As it turns out, Moonves’s sudden disappearance was the lead-in for the first two competitions of the summer, where eight houseguests will search for the host and the other eight will search for the HoH relic. At the end of the first competition, where contestants had to build a bridge connecting them to a collection of doors emitting audio prompts, Zach Cornell rescued Moonves from The Mastermind’s Lair.

While Moonves’ disappearance was short-lived, the introduction of The Mastermind, an ominous figure in a creepy red mask, teased some of the numerous secrets of the house, including the HoH relic at the heart of the night’s second competition.

The second half of the contestants were challenged with finding the true HoH relic. While some of the contestants quickly selected false relics, Jimmy Heagerty’s patience won the second competition, foiling the plans of the mysterious Mastermind.

Following the competitions, Moonves revealed that Zach won $10,000, while Jimmy won the power to select the only four contestants who will participate in the Head of Household competition.

What is Big Brother‘s next summertime mystery? Only time will tell…

Big Brother, Season 27, Wednesdays, Thursdays, and Sundays at 8/7c, CBS.