"Window" is a science fiction story by Bob Leman, published in 1980 and reprinted numerous times. It was nominated for the Nebula Award for best short story, and the influential science fiction publisher Donald A. Wollheim considered it one of the finest examples of the genre.
Plot
The prose is straightforward and to-the-point. The plot of the story involves the discovery of a three-dimensional window on a Victorian-style house and family. The window is created in a minor military research experiment that goes awry. The research involves studying the idea of channeling psychic powers through mnemonic words and phrases—in essence, spell casting.
To everyone's surprise, the research works, creating what the researchers and military men at first believe to be a window into the past. The three-dimensional window cannot be penetrated. However, every fifteen hours or so, the barrier between the two worlds becomes permeable for exactly five seconds.
In one of those moments of permeability, one of the researchers, nostalgic for the tranquil Victorian past he sees in the window, crosses over. The other researchers, left behind, are stunned, and frightened that the man who crossed over will inadvertently change the future. However, their surprise turns to horror when the youngest member of the Victorian family rushes towards the man who crossed over, leaps for his throat, and kills him. The rest of the Victorian family in the window then gorge on the remains of the researcher, devouring him utterly.
Before the researchers know what to do, the man in the Victorian-era window takes a thick, worn, Bible-like book, chants some words, and the window vanishes. Clearly, this alternate reality knows about magic spells, and knows how to use them.