I have read Elaine Pagels' work before (Gnostic Gospels) and have admired her work. I am not an expert in this aspect of history, but her works read well and she shows much knowledge of the material. She also places the issues addressed in an historical context.
Here, she explores the Book of Revelation, written, she says, by John of Patmos (an island off the coast of Turkey). She asks a number of questions in this book and strives to answer each (Page 3): "Who wrote this book? Why--and how--do so many people still read it today?" Pagels suggests that John began writing the book in 90 AD, probably after having fled his homeland in Judea.
Pagels discusses revelatory works, showing how John's book fit into this tradition. She also notes that, from the documents from Nag Hammadi, John's was not the only work of revelation. Why did his become part of the Biblical canon and not some other? She discusses the history and politics of the time and how the emerging church hierarchy wanted a definitive "Bible." She outlines the logic that ended up locating John's Book of Revelation within the canon.
This volume is well written, albeit a bit short. But it takes on a big subject and does not disappoint.