“What colour was the smoke?” is a text documentary about the fire in a public housing block, Grenfell Tower, that killed seventy two people in June 2017 in West London. The Government ordered an Inquiry under a Judge. The author followed the Inquiry for six months and uses the actual language of the firefighters, scientists and other professionals at the scene that night and above all the words of the bereaved, survivors and residents to present a condensation of the tragedy.