Four Sport Relief volunteers, comedian Nick Hancock, TV presenter Julia Bradbury, ex-snooker player Willie Thorne and celebrity cleaner Kim Woodburn, live on the streets of London to highlight the harsh reality of homelessness in the UK. The social experiment, led by John Bird, founder of the Big Issue, tests the celebrities' strength and self resilience as they struggle with isolation, fear, the cold and wet, and the effort of day-to-day survival.