Answer:
First, the fact that the poem begins on a "midnight dreary" establishes a very mysterious and bleak mood; it seems from the first line that odd and unaccountable things are going to happen. The speaker is filled with "fantastic terrors," and his heart beats quickly in anxiety and fear. We know that he has recently lost a woman he loved, Lenore, and when he suddenly hears a knock at his door, he opens it to find no one there and believes that it could be the ghost of his "lost Lenore." A phantom "rapping" at the door, a sound or which he cannot account through natural means, is certainly gothic.
