That she, on her return home, should have had sufficient presence of mind to toss these keys down in the same place from which she or her sister had taken them, argued well for her clear-headedness up to that moment.

The fever must have come on later--a fever which with my knowledge of what had occurred at The Whispering Pines, seemed the only natural outcome of the situation.
The next paragraph detailed a fact startling enough to rouse my deepest interest.

Zadok Brown, the Cumberlands' coachman, declared that Arthur's cutter and what he called the grey mare had been out that night.

They were both in place when he returned to the stable towards early morning, but the signs were unmistakable that both had been out in the snow since he left the stable at about nine.

He had locked the stable-door at that time, but the key always hung in the kitchen where any one could get it.
This was on account of Arthur, who, if he wanted to go out late, sometimes harnessed a horse himself.