The Guardian reports that Beren and Lúthien will be published in May 2017, and is edited by Christopher Tolkien and illustrated by Alan Lee.
The story was written in 1917 after Tolkien returned from the Somme, where he had served as a signaller. It is an “essential element in the evolution” of The Silmarillion, said the publisher, and the forthcoming book is the author’s son Christopher Tolkien’s attempt “to extract the story of Beren and Lúthien from the comprehensive work in which it was embedded.”