If this is non flash light and I think it is likely, as otherwise you'd have mentioned flash, then at one stop under it suggests that APX 400 has a reasonable latitude to be used at 800. On an emotional level the word that springs to my mind is "loneliness"
@pentaxuser yes, this was without flash. I was hesitant pushing APX400 (common wisdom suggests it’s not a great idea) but I was quite happy with how the roll turned out.