For over half a century, DNA has dominated science and the popular imagination as the “secret of life”. But over the last several decades, a quiet revolution has taken place. In a series of breathtaking discoveries, the biochemist Thomas R. Cech and a diverse cast of brilliant scientists have revealed that RNA—long overlooked as the passive servant of DNA—sits at the centre of biology’s greatest mysteries. In The Catalyst, Cech brings together years of research to demonstrate that RNA is the true key to understanding life on Earth, from its origins to our future in the twenty-first century. A gripping journey of discovery, The Catalyst moves from the early experiments that first hinted at RNA’s spectacular powers, to Cech’s own paradigm-shifting finding that it can catalyse cellular reactions, to the cutting-edge biotechnologies poised to reshape our health. We learn how RNA—once thought merely to transmit DNA’s genetic instructions to the cell’s protein-making machinery—may have jump-started life itself, and how, at the same time, it can cut our individual lives short through viral diseases and cancer. We see how RNA is implicated in the ageing process and explore the darker depths of the supposed fountain of youth, telomerase. And we catch a thrilling glimpse into how RNA-powered therapies—from CRISPR, the revolutionary tool that uses RNA to rewrite the code of life, to the groundbreaking mRNA vaccines that have saved millions during the pandemic, and more—may enable us to improve and even extend life beyond nature’s current limits. The Catalyst is a must-read guide to the present and future of biology and medicine.