I read a science fiction short story awhile back and can’t remember the author or title.

Could anyone give me a hand here?

The plot is as follows:

Aliens experimenting with teleportation suddenly transport a man from Earth to their world. They are very alien (they are described as looking somewhat like briefcases with tentacles, if I recall) and can’t even recognize that he’s alive and sentient. It’s a nightmare for him, but he manages to escape into a bizarre cityscape but ends up being killed when he tries to take a hostage. At least, I think that’s how it ends.