It is with great pleasure that I write the preface to the Bangladesh edition of Cornelia Rohde's remarkable book Catalyst: In the Wake of the Great Bhola Cyclone. Cornelia, (or Candy, as she is known to her friends), and her husband, Dr Jon Rohde, had been living in Dhaka for over two years when the cyclone struck on Nov 12, 1970. Jon was working in the Cholera Research Laboratory, where they had a lively circle of colleagues and Bengali friends. Catalyst is an account of how these friends jointly launched a relief operation that developed into long-term rehabilitation and development on the island of Manpura, an experience that changed their lives. The day after the cyclone struck, Cornelia met with a couple of friends and decided to act. One of them, Runi Khan, roped in a longstanding family friend, Fazle Hasan Abed (now Sir), who had recently returned from London to join Shell Oil Pakistan. Over the course of many months, he gave substantial administrative and logistical support from his residence in Chittagong, which became the base for their informal organization called HELP (Hatiya Emergency Lifesaving Project). In spite of difficulties with the Pakistani military and the civil administration, their relief work evolved into a five-year rehabilitation project on Manpura with the legendary Father Richard Timm coordinating the field work. Cornelia's description of their involvement is documented by personal archives, field notes, correspondence, first-hand observations, and over 100 black and white photos, making her group memoir an important addition to the history of Bangladesh. Recollections of those who were with them enhance the account.