If you want a book explaining the iconography behind Tibetan thangkas, this is pretty much the book you want. It goes into detail about the different Buddhas, protectors, historical figures, and demon protectors most commonly found in Tibetan art, what the different symbols and items around them represent, what stories are traditionally told of them, and how visualization techniques are used to further explain the intricacies of the Buddha-dharma in the Indian/Nepali/Tibetan tradition.
An invaluable resource for those embarking on the Tibetan Buddhist/Vajrayana path, or simply curious. I always recommend this book to newcomers who are confused by the myriad deities of Tibetan Buddhism and sometimes confusing symbolism and terminology. Basic Buddhist concepts are explained, and then there are detailed explanations of each of the most common Buddhist deities. Highly recommended.
An excellent introduction to Tibetan Buddhist visual art.
I think this book is also an excellent introduction to Tibetan Buddhism generally and would be a good book for someone who knows nothing about Tibetan Buddhism.