It is now conventional wisdom that biologist/crystallographer Rosalind Franklin was unfairly ignored by the Nobel Prize committee when the award was presented in 1962 Franklin's male colleagues James Watson and Francis Crick for their 1953 discovery of the Double Helix structure of DNA. This hour-long TV documentary scrutinizes the role that Franklin played in this momentous discovery, arguing that, were it not for her astonishing x-ray photograph, Watson and Crick would never have been able to make their discovery. Combining archival footage with newly filmed interviews of the DNA researchers' surviving colleagues, the film recounts Franklin's crucial Photo 51, achieved in her lab at King's College in London after 100 hours of exposure, and how knowledge of this photograph was casually mentioned by Franklin's co-worker Maurice Wilkins to James Watson, then working on the same research at Cambridge. Alas, because Rosalind Franklin died in 1958, existing Nobel Prize rules precluded mention of her name when awards were handed out four years later. Much of the material in this program is based on Franklin's private notebooks, inherited by Nobel Prize recipient Sir Aaron Klug, and also on Brenda Maddox' 2002 biography Rosalind Franklin: The Dark Lady of DNA. Secret of Photo 51 was first presented in the U.S. as an episode of the PBS anthology Nova.