Krauth (P) was a firefighter who responded to an alarm at Geller's (D) house. The house was under construction and vacant and when P arrived at the scene for the second time in as many days; the problem was a smoking oil stove in the basement that was used to dry plaster. P checked the upper levels of the home to ensure that no fire was present. P then started to return to the main floor, and the smoke obstructed his view and had layered such that P thought the smoke was the stairs. P fell when he stepped into empty space. P sued and won. The appellate division reversed.