The narrator gives a very detailed physical description of Ligeia – in fact, he has trouble remembering much else (like her last name, for instance).
Still, he has trouble defining her "expression" – something he can see in her eyes, but can never really explain. The closest thing he can come to a description is the quote from Joseph Glanvill.
The narrator tells the story of Ligeia's death:
He talks about how her love for him became more intense as she was dying.
He reads "The Conqueror Worm" aloud for her.
He hears her last words, which are the final part of the Joseph Glanvill quote.
He leaves Germany for England and moves into an abbey in a desolate part of the country.
He marries Lady Rowena, although he can't say why.
The narrator decorates his abbey in a bizarre way. He chalks up the weird décor to his intense addiction to opium.
The strangest room of all is the bridal chamber. The room is outfitted with coffins and its drapes are designed to create frightening optical illusions.
The narrator quickly comes to hate Lady Rowena.
Rowena succumbs to illness just a few months into their marriage, and the narrator is left to care for her. After recovering from one illness, Rowena becomes even sicker.
The narrator gives an account of Rowena's final hours:
He's high on a lot of opium and constantly having visions of Ligeia, but a few things stick out.
One night, Lady Rowena is really on the verge of fainting. When the narrator goes to grab some wine in order to revive her, he notices a couple of things: he feels as though an invisible object has passed him by, and he sees a shadow – cast by who knows what – in the middle of the carpet. He doesn't say anything about his visions because he's high on opium.
Right when Lady Rowena is about to take a sip of the wine, the narrator watches a few drops of ruby red liquid fall into her cup. Still, he's not sure if he's actually seen it happen or if he's just hallucinating on account of the opium.
After Lady Rowena dies, the narrator watches over her body. Still, he spends most of his time having intense visions of Ligeia.
The third night he hears a sob coming from Rowena's bed. He notices that life has returned to her body. The life just as quickly seeps out of her, however.
A cycle begins: Rowena comes back to life and then dies again just as quickly. Each time, her revival is more intense and her dead state more corrupted, as if she's been lying in a tomb for weeks instead of days.
All the while, the narrator is having intense visions of Ligeia.
Finally, early in the morning, Lady Rowena rises from her bed and moves toward the narrator. The narrator leaps up toward Rowena and, in doing so, notices that she seems to have grown taller.
When he tries to reach out and touch her, Ligeia moves away.
After Rowena removes her shroud, the narrator sees "huge masses" of black hair. He realizes then that he's looking at the one and only Lady Ligeia.