Great strides have been taken in preventing and treating heart disease, yet it remains one of the biggest serial killers and our understanding of its causes is incomplete. This lecture describes how clues from population databases, modern genetics, and detailed investigations in patients have implicated steroid stress hormones in heart disease and how this has led to the development of new drug treatments. Brian Walker is Professor of Endocrinology at the University of Edinburgh. This lecture is part of the Medical Detectives, a series of public lectures that show how keen detective work is still essential for 21st century doctors: http://www.ed.ac.uk/news/events/medical-detectives/ Recorded on 18 October 2012 in the Anatomy Lecture Theatre at the University of Edinburgh.