Rachel Reilly, winner of Big Brother 13, was unveiled as the "mystery houseguest" competing again this summer on season 27.CBS had been teasing a secret player all week and dropping clues on social media as to who it was.

Popular reality show "Big Brother" premiered this week, featuring two Texas residents who say they are up for the challenge.

Big Brother follows a group of people living together in a house outfitted with more than 100 cameras and 100 microphones, recording their every move 24 hours a day. Each week, someone will be voted out of the house, with the last remaining Houseguest receiving the grand prize of $750,000.

The premiere of Big Brother Season 27 is just days away, but that's not soon enough for some. The house and theme were revealed, as well as the existence of a mystery 17th Houseguest. CBS decided to tease fans just a bit more by dropping a five-second promo featuring five of the new contestants.