Chapter 1 is the introductory chapter. It introduces the reader to the two seemingly complementary global imperatives of ‘dealing with the past’ and ensuring non-repetition of mass atrocities. The chapter sets up a conundrum about transitional justice, ontological (in)securities, and non-recurrence. It then proceeds with a summary of the book’s key questions and core arguments. The chapter subsequently puts forward a brief history of the evolution of transitional justice as a global project, a vehicle of peace as well as security, discussing the claimed intersections between transitional justice and ‘Never Again’. This is followed by brief notes on methodology and contributions of the book. In outlining the contributions, the chapter demonstrates how the book interacts with and enriches scholarly knowledge in the field of transitional justice as well as in ontological security studies. Finally, the chapter introduces the outline of the book with brief chapter summaries.