Plagued by typhus on the Eastern Front, the German army turned for help to the eccentric Polish zoologist Rudolf Weigl, who had developed a vaccine for the disease in the 1920s. Outraged by Nazi atrocities and prompted by his Christian faith, however, Weigl made his laboratory a safe haven for scientists, who used their protected status as a front for a sabotage campaign, sending illegal doses of the vaccine into the Polish ghettos while shipping gallons of the weakened serum to the Wehrmacht. Here the author of Vaccine and Ripe: The Search for the Perfect Tomato also tells the story of one of Weigl's refugees, Jewish immunologist Ludwik Fleck, imprisoned at Buchenwald and offered a chance to save his own life if he will work for his captors. "[This is] an unforgettable book."—Kirkus Reviews (starred review)