Documentary on nature's ultimate abyss, the black hole. It is the darkest thing in the universe and its gravity is so powerful that not even light can escape. Most start out as brilliant stars which, after millions of years, eventually collapse forming a bottomless pit from which there is no escape. Narrated by actor John Hurt and directed by award-winning documentary filmmaker Richard Smith, the program is a journey into interstellar space to explore these mysterious "prisons of light", via an imaginary computer-generated space ship. Guides for the journey include Professor Stephen Hawking, Britain's Astronomer Royal Sir Martin Rees, and Homer Simpson. The program also examines the history surrounding black holes, from the first conception of them in 1859 to the present day.