I read this 1992 book to refresh and update my thinking on the discoveries at Qumran. I found it very helpful. The first chapter by Hershel Shanks gives a good overview of where the research is at this present time. The second chapter was of particular interest to me because James Vanderkam (Ph.D. from Harvard) argues for the Qumran community being Essene, a common but unpopular view in his circles today. The book is not long and has some nice pictures. It is published by the Biblical Archaeological Society.