By John Powell – GlobalTV.com

Someone better call Jessica Fletcher, Lt. Columbo, Thomas Magnum or Leroy Jethro Gibbs and even they might not be enough to investigate all of the mysteries in the Big Brother house.

Big Brother’s ‘Summer of Mystery’ has turned the house into the ‘Hotel Mystère’ where things are already proving not to be what they seem especially when it comes to the format, rules of the game.

But first, host Julie Chen-Moonves and the newly introduced ‘HoH’ Relic’ were snatched by a mysterious masked figure named The Mastermind who addressed the houseguests over the plasma TV in the front room after hijacking the game. Who knew that an ‘HoH Relic’ was required to start the game but fans have come to ‘expect the unexpected’ from Big Brother.

The houseguests were divided into two teams. One would rescue Julie while the other would located the missing relic. That of course ushered in two challenges, the winners of which would not only complete the main objective but also win a special power for themselves.

Zach Cornell, the marketing manager from Georgia, saved Julie while Jimmy Heagerty, the AI consultant from Washington, found the true HoH Relic.

Zach won a $10,000 reward for locating Chen-Moonves.

Jimmy’s reward was a little bit different.

“You have been granted an extremely valuable reward. For the first HoH competition only four houseguests will be playing and it is up to you Jimmy to choose those four competitors. It can be anyone you like including yourself,” Chen-Moonves revealed to Jimmy and the rest of the house.

After being given some time to chat with the other houseguests Jimmy picked himself, Adrian, Ashley and Vince to compete.

In a competition to destroy The Mastermind’s lair, the winner and the first Head of the Household of the season was Vince.

Vince didn’t have much time to celebrate as four – count them FOUR – game-changing twists were dropped on his HoH reign and the rest of the season.

Firstly, The Mastermind introduced Big Brother season 13 winner Rachel Reilly as another contestant, player.

Secondly, the AI Arena competition from last year was returning as the Block Buster competition. The nominees will compete in a challenge on eviction night with the winner taking themselves off the block.

Thirdly, the HoH will be nominating three houseguests every week.

Fourthly, The Mastermind revealed they had an accomplice working with them the entire time.

“Your new roommate (Rachel Reilly) is officially in the game but she is not the seventeenth houseguest. You see, I have had an accomplice this whole time and my accomplice is one of you…I told my accomplice that if they could do all of this and remain undetected they would become a real houseguest meaning 17 of you will be vying for the grand prize but if the majority of you can successfully determine who my accomplice is they will be immediately removed from the house and only 16 of you will be playing this summer,” Mastermind told the houseguests.

Who is the accomplice? Who will Vince nominate? Check out the next episode on Global TV. It will be another 90-minute episode on Sunday, July 13th at 8:00-9:30 PM, ET/PT.

Note that the series will air Wednesdays (8:00-9:30 PM, ET/delayed PT) expanded from its regular 60-minute episodes, followed by hour-long shows on Thursdays – featuring live evictions – and Sundays (8:00-9:00 PM, ET/delayed PT).

On Fridays, watch Big Brother: Unlocked as three BB All-Stars offer never-before-seen broadcast footage from the house, exclusive interviews, surprise guest appearances and unprecedented behind-the-scenes access. Former Houseguests share firsthand insight and expertise as they analyze gameplay, assess the competition and give their insider’s perspective every other Friday starting Friday, July 25 (8:00-9:00 PM, ET/PT).

Return here all season long for interviews, spoilers and live feed updates all season long.

You can catch up on the latest episodes here.