A group of 19 people selected from a national search share a House sealed from the outside world for up to 100 days. Watching over these Housemates is Big Brother - heard only via a voice. He is the all-seeing all-knowing authoritarian figure who monitors the Housemates' every move. Every week Housemates nominate each other for Eviction in a secret ballot. The viewers then vote to decide who will be Evicted. The last person left wins the major cash prize.