This document summarizes an online book about unleashing learner agency through heutagogy (self-determined learning). It provides an overview of the book's 18 chapters, grouped into sections on theory, learning, barriers, and learners. Each chapter summary briefly describes the chapter's focus and key ideas. Overall, the book argues that heutagogy empowers learners by giving them control over their learning and allowing education systems to shift from authoritative to learner-centered models.