Rosalind Franklin took Photo 51 in May 1952 at King's College London, and it remains one of the most important images in scientific history. The X-ray diffraction photograph showed DNA's helical structure so clearly that Francis Crick later admitted he and James Watson would have taken much longer to solve the puzzle without it. But Franklin never knew they'd seen her unpublished data. Her colleague Maurice Wilkins showed Watson the photograph without her permission in January 1953, and within weeks, Watson and Crick had their famous model. Franklin wasn't just a talented technician who happened to take a good picture. She was a physical chemist with expertise in X-ray crystallography who'd already made significant contributions to understanding coal and graphite structures during World War II. Her work at King's College involved painstaking mathematical analysis of diffraction patterns, and she'd concluded by early 1953 that DNA had two helical chains. Her research notebooks show she was methodical, rigorous, and closer to the answer than anyone else. She just didn't rush to publication the way Watson and Crick did. The professional environment at King's College was toxic for Franklin from the start. She arrived in January 1951 expecting to lead the DNA work, but Wilkins assumed she was his assistant. The common room at King's didn't allow women, and Franklin ate lunch alone in her laboratory. Wilkins later described her as difficult and aggressive, the standard dismissal for women who refused to be deferential. Franklin left King's for Birkbeck College in March 1953, just as Watson and Crick published their Nature paper citing her work only in passing. At Birkbeck, Franklin switched to studying viruses and produced groundbreaking work on the tobacco mosaic virus and poliovirus. She published 17 papers in five years, traveled internationally to present her research, and built a respected research group. But she'd been exposed to X-rays for years without adequate protection, and in 1956 she was diagnosed with ovarian cancer. She continued working through brutal treatments, still publishing and supervising students, until her death on April 16, 1958, at age 37. Watson, Crick, and Wilkins shared the 1962 Nobel Prize in Physiology or Medicine for discovering DNA's structure. The Nobel committee doesn't award prizes posthumously, so Franklin was ineligible regardless of her contributions. Watson's 1968 memoir The Double Helix portrayed Franklin as an obstinate woman who didn't understand her own data, a characterization so offensive that Crick tried to stop publication. Only in recent decades have historians fully documented Franklin's central role, and even now, most people learn about Watson and Crick in school while Franklin gets a footnote. Franklin's nephew Aaron Klug, who won his own Nobel Prize in Chemistry in 1982, spent years after her death analyzing her notebooks and defending her legacy. He demonstrated that she'd independently reached correct conclusions about DNA's structure and had been on the verge of publishing when Watson and Crick beat her to it. Her colleague Anne Sayre published a biography in 1975 that challenged Watson's sexist portrayal, but the damage to Franklin's reputation had already spread through popular culture. The European Space Agency named a Mars rover after her in 2022, and her face appeared on British currency in 2024, belated recognition that does nothing to change what happened.