That night, Frank Zappa and the Mothers of Invention were playing at the casino. Someone in the audience fired a flare gun into the ceiling and set the building on fire. Ian Gillan later remembered seeing two flares fired by someone sitting behind him, landing in the upper corner of the building and quickly setting the whole place ablaze. Zappa stopped the show and helped people get out in an orderly way. Deep Purple watched the fire from a nearby restaurant, and when it was all over, the smoke had spread across Lake Geneva, stretching in front of the casino. That exact image gave Roger Glover the title. “Smoke On The Water.” From there, Ian Gillan wrote the lyrics as an account of that entire ordeal surrounding the recording of Machine Head.