Drawing on new archival discoveries, this book presents an authoritative reconstruction of David Jones's The Grail Mass, the unfinished and unpublished project from which came both his masterpiece The Anathemata - a work described by W.H. Auden as 'one of the most important poems of our times' - and The Sleeping Lord and other fragments, his final collection. With detailed commentary on the development and reconstruction of the text, this edition provides a full picture of Jones's literary endeavours over the second half of his life and further establishes his status as a major figure in the first wave of British modernist writers alongside T.S. Eliot and James Joyce. In addition to the text of The Grail Mass, this edition includes a number of unpublished fragments by Jones that emerged from this larger project, complete with textual commentaries.