Answer:
A gallant knight meets a beautiful maiden while out riding one day. He immediately becomes infatuated with this woman, allowing her to feed him roots and berries. Later, he realizes that he has come under the woman's thrall and that she controls him mercilessly.
The speaker comes across a lonely knight sitting in an arid field. The first three stanzas of the poem consist of questions the speaker asks of the knight.
In stanza four, the knight begins to tell of his encounter with the beautiful woman ("belle dame") of the poem's title. She sang him songs, fed him roots, and slowly drew him under her spell.
In a dream, he meets pale kings and princes who tell him that he's being controlled by the woman and that she'll show him no mercy. He's abandoned in the arid field, where he meets the poem's speaker.
