In the early weeks of 2020, a small group of scientists recognized the growing danger of an emerging microbial threat. They quickly organized their colleagues into a collaborative team that met weekly, dedicated to innovating new approaches to combat COVID-19 as the pandemic unfolded. The resulting CrisiScience Collaborative would swell to hundreds of high-profile members, including Nobel laureate scientists, engineers, and business leaders—all of whom volunteered to anticipate and solve problems. Their activities were performed in the background, and while going mostly unnoticed, their contributions would save countless lives. Behind the Mask is the largely unknown story of selfless acts and innovative thinking during the earliest days of COVID-19 when so much was unknown and the future felt uncertain. Fundamentally, this is a story of cooperation during a crisis that demonstrates what can be done when we unite against a common enemy.