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.

"Big Brother" Season 27 contestants better grab a life vest, because star Rachel Reilly is checking in as the 17th houseguest

Season 27 of Big Brother premiered last night, and though we're only in the early stages of the season, it's clear that Hotel Mystère is going to be packed with mystery and intrigue. The episode began with this season's houseguests further introducing themselves,