This book offers a theory and methodology of transmedia arts activism within the technocultural and sociopolitical landscape of expanded documentary production, distribution, reception and participation. Through a detailed analysis of the author's transmedia project on indigenous and minority language endangerment and revival that consists of the feature-length documentary Tongues of Heaven and the companion web application Root Tongue: Sharing Stories of Language Identity and Revival, she reveals the layers and depths of a critical arts practice when confronted with complex sociopolitical issues while working with multiple communities across territorial/national boundaries. In the context of the growing field of transmedia documentaries, the author discusses the potentials and benefits of a critical design practice and production ethics that can transform this field to pilot new collaborations in documentary and digital media platforms towards a third digital documentary.