The search for a “cure” for cancer is the greatest epic in the history of science. It spans centuries and continents and is full of its share of heroes, villains, and sudden vertiginous twists. This episode follows that centuries-long search, but centers on the story of Sidney Farber, who, defying conventional wisdom in the late 1940s, introduces the modern era of chemotherapy, eventually galvanizing a full-scale national “war on cancer.” Interwoven with Farber’s narrative is the contemporary story of little Olivia Blair, who at 14-months old is diagnosed with T-cell acute lymphoblastic leukemia, which spreads to her brain and spinal column. The film follows her as she and her parents struggle with the many hardships and decisions foisted upon a cancer patient. She remains in full remission a year after her diagnosis, but is still on her journey to finish her three-year treatment plan.

This episode picks up the story in the wake of the declaration of a “war on cancer” by Richard Nixon in 1971. Flush with optimism and awash with federal dollars, the cancer field plunges forward in search of a cure. In the lab, rapid progress is made in understanding the essential nature of the cancer cell, leading to the revolutionary discovery of the genetic basis of cancer. But at the bedside, where patients are treated, few new therapies become available, and a sense of disillusionment takes hold, leading some patients and doctors to take desperate measures. It is not until the late 1990s that the advances in research begin to translate into more precise targeted therapies with the breakthrough drugs Gleevec and Herceptin. Following the history during these fraught decades, the film intertwines the contemporary story of Dr. Lori Wilson, a surgical oncologist who is diagnosed with invasive breast cancer in both breasts in 2013. Her emotional and physical struggles with the disease provide a bracing counterpoint to the historical narrative.

This episode picks up the story at another moment of buoyant optimism in the cancer world: Scientists believe they have cracked the essential mystery of the malignant cell and the first targeted therapies have been developed, with the promise of many more to follow. But very quickly cancer reveals new layers of complexity and a formidable array of unforeseen defenses. In the disappointment that follows, many call for a new focus on prevention and early detection as the most promising fronts in the war on cancer. But other scientists are undeterred, and by the second decade of the 2000s their work pays off. The bewildering complexity of the cancer cell, so recently considered unassailable, yields to a more ordered picture, revealing new vulnerabilities and avenues of attack. Perhaps most exciting of all is the prospect of harnessing the human immune system to defeat cancer.