Exploring the fear that paralysed London as the disaster entered day three, focusing on the public not knowing or understanding what was happening, the government's lack of action, to the undertakers working 24 hours a day. As the story concludes, Dr Xand Van Tulleken and Raksha Dave reveal why and how the smog lifted, and London metaphorically and physically began to breathe again.

• Xand van Tulleken
• Raksha Dave