For readers of The Making of the Atomic Bomb and Code Girls, who want stories about the tech behind military successes and the maverick groups that generate historic innovations This is the previously classified story of one group of scientific researchers—men and women—who exposed themselves to extraordinary risks to make D-Day a success. On the beaches of Normandy, two summers before D-Day, the Allies attempted an all but forgotten landing. Of the nearly seven thousand Allied troops sent ashore, only a few hundred survived the terrible massacre, and the reason for the debacle was a lack of reconnaissance. The shore turned out to be impassable to tanks. The Nazis had hidden obstacles in unexpected places. The fortifications were more numerous—and deadly—than imagined. The Allies knew they needed to take the fight to Hitler on the European mainland to end the war, but they could not afford to be unprepared again. A small group of eccentric researchers, experimenting on themselves from inside pressure tanks in the middle of the London air raids, explored the deadly science needed to enable the critical reconnaissance vessels and underwater breathing apparatuses that would enable the Allies’ dramatic, history-making success during the next major beach landing: D-Day. Based on top secret documents only recently declassified and hunted down by Rachel Lance, this is the story of a band of maverick, hard-drinking submarine researchers, led by the controversial, brilliant biologist and communist sympathizer JBS Haldane as well as the intrepid Dr. Helen Spurway. Without their lab and its wartime work, neither SEALs nor submarines could prowl the ocean the way they do today.