The plot of Poe's tale essentially involves a woman who dies, is buried, and rises from the grave. But did she ever die? Near the horrific finale of the tale, Usher screams: "We have put her living in the tomb!" Premature burial was something of an obsession for Poe, who featured it in many of his stories. The decay of the house certainly foreshadows the decay of both Usher and his sister,
"the crumbling condition of the individual stones. In this there was much that reminded me of the specious totality of old wood-work which has rotted for long years in some neglected vault, with no disturbance from the breath of the external air. Beyond this indication of extensive decay....."
Poe specialized in Gothic romantic. His stories tend to have a morbid dark appeal to them with eccentric and insane characters.