Great Britain’s electricity network is undergoing a major transformation as it moves from a system based on burning fossil fuels in central power stations to one dominated by distributed renewable energy; this brings with it a new set of risks. In parallel, the move to electronic documentation and communication is increasing the dependence of society on an ‘always-on’ electricity supply. Assessing the level of dependence is difficult, as full-scale experimentation is not practicable and a desktop analysis of situations involving a large number of human interactions is unlikely to be representative. In December 2015, Storm Desmond resulted in a blackout affecting more than 100 000 people in Lancaster, UK. This provided a unique case study that allowed researchers to investigate how society responds to a widespread loss of the electricity supply.