“I am ‘full up’ with atrocities and horrors,” wrote Roger Casement in a letter to the British Foreign Office in March 1911. Casement, a diplomat and activist, had just returned to London from the Amazon jungle, where he had spent several months investigating the rumoured exploitation of Barbadian workers—at that time, British subjects—by a rubber manufacturing company. The Peruvian Amazon Company, Casement found, was abusing not only its Barbadian employees, but also enslaving and terrorizing the local Indian population. In the years following these revelations, until his death in 1916, Casement worked tirelessly to bring the man he considered responsible—the Peruvian rubber baron, Julio César Arana—to justice. In “The Devil and Mr. Casement,” British historian Jordan Goodman offers a dispassionate account of Casement’s struggle to expose and put an end to the atrocities wrought by Arana’s company in the Putumayo River Basin of northern Peru. But while Goodman’s chronicle of colonial-era corruption is admirably detailed, Goodman fails to identify the ethical complexities of Casement’s humanitarian project.

In the same way that details of the violence committed by and against the employees of the Peruvian Amazon Company surfaced slowly in the British press in the three years leading up to the Casement’s 1912 report, Goodman deploys his sources gradually, amassing eyewitness accounts alongside official reports. Goodman cites descriptions of gang rape, the torture of children (by burning their hands and feet until they betrayed the whereabouts of their parents), and deliberate regimes of starvation—all tactics to maintain an atmosphere of terror in which the Indians would not dare to fall short of the rubber-collecting quotas.

The egregiousness of Arana’s crimes is most bluntly expressed, though, in a single statistic from Casement’s report: between 1906 and 1911 the Indian population of the Putumayo region declined from 50,000 to 8,000. These deaths were not part of a systematic extermination campaign, but were the products of a deep vein of institutionalised violence symptomatic of colonial subjugation.

“The Devil and Mr Casement” succeeds in bringing the principal players of the story to life in brisk, unadorned prose, and with frequent recourse to historical sources. We cannot help but share Goodman’s obvious admiration for Casement, who had established his humanitarian credentials in 1903 with a report exposing the wholesale abuse of the native population—again, in the name of rubber production—of the Congo Free State under King Leopold II of Belgium. “Wherever he went and whomever he met, Roger Casement rarely failed to make a deep, lasting, highly favourable impression,” Goodman tells us. He quotes a fellow activist, Edmund Morel, recalling his first impressions of Casement: “I saw before me a man, my own height, very lithe and sinewy... A long lean, swarthy Vandyke type of face, graven with power and withal of great gentleness.” Casement emerges as a brave and sensitive campaigner with a strong sense of moral purpose, dogged in his pursuit of Arana, who, having driven out all competition for rubber-production in Iquitos by 1907, had succeeded in “turning the Putumayo region into his personal fiefdom.”

Goodman’s account of these events is commendably clear, but he often presents the story and its characters in reductively simple terms. As the book’s title suggests, Goodman frames Casement’s clash with Arana as a battle between good and evil, between defenders and abusers of human rights, between heartfelt humanitarianism and ruthless capitalism. This is, to an extent, justified, given the enormity of the crimes committed against the native population of Putumayo by the Peruvian Amazon Company in the name of Europe’s ever-increasing demand for rubber.

However, Goodman’s sources betray the murkier moral landscape of the era of high imperialism—the book’s subtitle, “One Man’s Battle for Human Rights in South America’s Heart of Darkness,” makes explicit allusion to Joseph Conrad’s famous novella, especially apt given the fact that Conrad and Casement met in 1889 in the Congo Free State. Casement’s own description of Arana recalls “the unseen presence of victorious corruption” that Marlow senses in Colonel Kurtz. “There is no doubt the brute has courage—a horrid, fearful courage, and endurance, and a cunning mind too... This is an educated man of a sort, who has lived long in London, knows the meanings of his crimes and their true aspect in all civilized eyes.”

The worrying lack of “civilization” in the Putumayo basin crops up repeatedly in Casement’s correspondence and in his 1912 report. Troublingly, though, Casement’s vocabulary goes unremarked upon by Goodman, who appears not to notice that Casement, at least in the early stages of his investigation, did not view Arana’s dealings in the Putumayo in opposition to some universal ethical standard, but to the imperial “mission civilisatrice.” Casement is dismayed, for example, that “there are no civilized authorities in that part of the country,” because it means that Arana’s agents are able to “conquer and subdue the Indian, who is a grown-up child.”

It is important to recognize Casement’s immanence within the imperial system, even as he was enraged by the abuses it engendered, and pointing out this ambivalence would not undermine Casement’s achievement as a campaigner, nor cast doubt on the authenticity of his humanitarian sentiment, but simply illuminate the complexity of his predicament and character. Instead, Goodman misses the opportunity to present Casement’s story as emblematic of the conflicted, traumatized, and transitional consciousness of colonial operators in the early twentieth century. Furthermore, in attributing to Casement an unalloyed concern for “human rights,” Goodman simplifies where he should have complicated: while the Putumayo revelations contributed much to the burgeoning discourse of human rights, the movement would not gain momentum until the Interwar years and beyond, as a product of the agonized transitions to independence made by many former colonies, and, of course, the fallout from the nakedly imperialist ambitions of the Third Reich.

The strength of “The Devil and Mr Casement” lies in the thoroughness of Goodman’s research and his assiduous fidelity to the historical record. But the tension of Goodman’s narrative ultimately slackens under the weight of his facts, which are deployed too densely, and without enough reflection, to make “The Devil and Mr. Casement” as satisfying and challenging as it could—and should—have been.