Daniel Koehler is the Founding Director of the German Institute of Radicalization and De-Radicalization Studies (GIRDS) and a leading expert on terrorism, violent extremism, radicalization, and deradicalization. He is member of the Editorial Board of the International Centre for Counter-Terrorism in The Hague and a Research Fellow at the Polarization and Extremism Research and Innovation Lab of the American University in Washington, DC.

• Foreword; Preface; 1. Betraying the cause? Side-switching and violent extremism; 2. Nation, race and anti-semitism: switching to far-right extremism; 3. Joining the far-left; 4. Fighting on the path of Allah: joining Islamic extremism from the far-right and far-left; 5. Who are extremist side-switchers and what drives them? Towards a theory of motivations and defector lifecycles; 6, Breaking the cycle: learning how to improve counter-radicalization, counterterrorism and deradicalization programs; 7. Conclusions.

'A tour de force, offering an original take on a neglected aspect of extremist radicalization: the strange phenomenon of extremist side-switchers. Koehler's gripping narrative account of defectors who migrate across extremist groups and ideologies is both absorbing and trailblazing, shedding important new light on critical vulnerabilities during de-radicalization and disengagement processes.' Cynthia Miller-Idriss, Professor in the School of Public Affairs and the School of Education, American University, USA