Before beginning the lay, the narrator says that laüstic is the Breton word for nightingale.

In the town of St. Malo, two knights live in adjoining dwellings. One of the knights is in love with his neighbor’s wife, who returns his affections. They keep their love secret, exchanging many looks and gifts safely. However, given that they cannot “meet and take their pleasure with each other,” they spend much of their time looking at each other through the window at night (94). The lady’s nocturnal window-gazing attracts her husband’s attention, and she explains that she is awake to listen to the nightingale’s song.

The husband responds by setting traps to ensnare the nightingale. When he succeeds, he presents the bird to the lady and kills it in front of her. The devastated lady recovers the corpse and sends it to her beloved. The knight places the nightingale corpse in a vessel covered with precious stones, which he keeps with him always.