"Be that word our sign in parting, bird or fiend!" I shrieked, upstarting – "Get thee back into the tempest and the Night's Plutonian shore! Leave no black plume as a token of that lie thy soul hath spoken! Leave my loneliness unbroken! – quit the bust above my door! Take thy beak from out my heart, and take thy form from off my door!" Quoth the Raven "Nevermore."
Finally, he completely loses it. That last "Nevermore" is the final straw, and he jumps up and tells the bird to get lost (97).
He directs it to get back to the storm and the evil night it came from (98).
He tells it not to leave any trace, not even a feather ("black plume"), and to take its lies elsewhere and leave him to his loneliness.
He tells the raven to get off the statue, to take his beak out of his heart, and, basically, to go to hell. To which the Raven says, "Nevermore." This bird is here to stay.
And the Raven, never flitting, still is sitting, still is sitting On the pallid bust of Pallas just above my chamber door; And his eyes have all the seeming of a demon's that is dreaming, And the lamp-light o'er him streaming throws his shadow on the floor; And my soul from out that shadow that lies floating on the floor Shall be lifted – nevermore!
All of a sudden, we switch to the present tense. This isn't a story from the past, it's right now, and the raven is still there.
He has turned into a kind of statue himself, a glowing, scary demon statue, whose shadow is cast across the floor. That shadow has trapped the speaker, imprisoned his soul.
We start out hearing a story about a talking raven on a dark night, and we end up watching a man descend into his own personal hell.