The Footprint in the Sky
John Dickson Carr
She awoke out of confused dreams; awoke with a start, and lay staring at the white ceiling of her bedroom for a minute or two before she could convince herself it was anything but a dream. But it was a dream.
The cold, brittle sunlight poured in at the open window. The cold, brittle air, blowing the curtains, stirred a light coating of snow on the window-sill. It stirred briskly in that little, bare room; it should have set the blood racing, and Dorothy Brant breathed it deeply.
Everything was all right. She was at the country cottage, where she and Dad and Harry had come down for the skating on the frozen lake; possibly even a little mild skiing, if the snow came on according to the weather forecast. And the snow had fallen. She should have been glad of that, though for some reason the sight of it on the window-sill struck her with a kind of terror.
. . .