Cuddy has a TED talk that is a reasonable introduction to the content in this book.

This book talks a fair bit about body language, but instead of what it tells others, the primary focus is about using body language to communicate with yourself, and uses her own academic work, along with some others, to allow yourself to behave with confidence and set yourself up to project your genuine belief in yourself of your ideas to others. The TED talk might be sufficient for you, but if you want to go a touch deeper and get basic information about the research and methodology this is a sold read.