The Dráp Niflunga is a short prose section in the Poetic Edda between Helreið Brynhildar and Guðrúnarkviða II. Henry Adams Bellows notes in his commentary that the purpose of the section is to serve as a narrative link between the poems.
In the preceding sections, both Sigurd and Brynhildr have died and this section deals with how Brynhild's brother Atli becomes Gudrun's second husband and with how Atli avenges Brynhild's death by slaying Gudrun's brothers Gunnar and Hogni.
This is Henry Adams Bellows' translation of the section: