According to its blurb, Underground Asia “turns our understanding of 20th-century empire upside down”. That is going too far. It is, however, an extremely valuable addition to the scholarship of modern revolutionary movements, adding much new detail from an array of multilingual sources. At times, Harper’s objectivity slips, and he makes little attempt to disguise either his admiration for his subjects or his contempt for the colonial regimes they battled to overthrow. The revolutionaries were undoubtedly brave, but also often narcissistic and self-absorbed.