"Ritual Theatre - The Power of Dramatic Ritual in Personal Development Groups and Clinical Practice." It's published by Jessica Kingsley Publishers and available through Amazon.
The book is a collaboration of different styles of work with ritual theater, including a chapter on psychodrama by Sylvia Israel and Elizabeth Plummer, both psychodramatists in California -- and edited by Claire Schrader in London.
See a preview of their chapter Psychodrama and Ritual Theatre here.
Here's a link to Claire's blog where she talks more about the book and her own influences from different aspects of Ritual Theatre including African shaman Malidoma Somé.