As the title indicates, this book presents in very readable form the life of H. P. Blavatsky and her considerable influence on important 20th century figures from Einstein to Elvis (he read out passages from her books on stage). But it does something else that very few works on HPB have done before, and that is to present major themes in Blavatsky's thought and work, with ample quotes from her letters and writings. Even theosophical writers have tended to focus on Madam Blavatsky's colorful character, adventures, and occult manifestations, rather than bring to the fore the depth of her insights.
Blavatsky has been unfairly dissed by writers who assume from the start that Masters (or Bodhisattvas) could never exist and 'occult' phenomena are all fraudulent, assumptions that run counter to thousands of years of Asian records and tradition. In that sense, the fact that Cranston is an unabashed believer probably adds to the value of the work. Where she falls short is in failing to mention Blavatsky's suicide attempt, contacts with the Russian secret service, and other more human, less saintly aspects, all verifiable by documentary evidence. Also, there were several mistakes in the initial edition, so it is better to get later editions if possible.
All in all, for the reader who is interested in getting a sympathetic, intelligent account of Madam Blavatsky's teachings, without having to wade through the 20 thick volumes she penned, this is the book.