It would be a wonderful thing if Christopher Dickey’s new book, Our Man in Charleston: Britain’s Secret Agent in the Civil War, could be read solely as a piece of fascinating and entertaining history. After all, this story of the heretofore forgotten British diplomat Robert Bunch has all the elements of a good political thriller: government espionage, double-crossings, intrigue, and characters ranging from mysterious to larger-than-life. There are high stakes, too — Bunch was Britain’s consul in Charleston from 1853 to 1863, and was instrumental in preventing his country from intervening in the American Civil War.

The book also, however, offers a head-on view into not only the abject horrors of slavery and the transatlantic slave trade, but also the sickeningly bankrupt morality of 19th-century Charlestonians in particular, and Southerners in general, for whom slavery was an institution to be preserved and expanded at any cost — even, as we all know, the cost of war. In light of the recent Emanuel AME church shooting and the conflict around the removal of the Confederate flag from the S.C. Statehouse grounds, Our Man in Charleston is, sadly, a highly relevant look at the society that started the War Between the States.

The fact that preserving slavery was the reason for South Carolina’s secession is not news to anyone who has studied the Civil War academically, rather than buying into the pervasive mythology that glorifies the Confederacy as a bright beacon of independence and states’ rights while smoothly glossing over the slavery issue as if it were just a mild unpleasantness. But let’s be honest: most of us haven’t really studied the Civil War. The majority of books on the subject tend to be geared toward military buffs, while even those for a wider audience — Tony Horwitz’ Confederates in the Attic comes to mind — do little, if anything, to show just how central slavery was to the cause of secession, especially in South Carolina.

Slavery is also why, seven years prior, Bunch landed in Charleston. As an agent of Great Britain, which ardently opposed slavery and had made it a mission to end the practice, Bunch’s original mission in the Holy City was to negotiate an end to the state’s barbaric Negro Seaman Act. The law stated that any free black sailor whose ship put in at Charleston Harbor would be thrown into jail until the ship was ready to leave.

Fulfilling this mission required Bunch, who was wholly appalled by slavery as an institution, to lead a double life. If he was going to persuade those in power that the law should be changed, he had to ingratiate himself with Charleston society while hiding his inward disgust.

The one place he could vent that disgust was in his confidential dispatches to his superiors in England. Take this letter from January of 1854, one of a great many from which Dickey quotes: “The frightful evil of the system is that it debases the whole tone of society — for the people talk calmly of horrors which would not be mentioned in civilized society. It is literally no more to kill a slave than to shoot a dog.”

It was this disparity between the persona Bunch presented to the Charleston elite, and his true feelings as represented in his letters, that originally drew Dickey to him as a potential subject for a book. Dickey, a longtime foreign bureau chief for Newsweek, The Washington Post, and now for The Daily Beast, had originally been working on a book about the British explorer and scholar Sir Richard Francis Burton when he discovered Bunch. “There are lots of great biographies on Burton, but all of them have one missing piece, which is ‘What did he do for two months in the summer of 1860, when he was in the U.S.?'” Dickey says.

Dickey spent 10 or 12 years, off and on, researching and trying to find the answer to that question, but along the way he hit upon a complication — he didn’t really like Burton, and didn’t want to write a book about him. But the time he’d spent on the question was hardly lost. “In the course of investigating all this, I found other figures who were little-known or unknown, and had written voluminous dispatches not only to the Foreign Ministry in London, but to other ministers [ambassadors] in Washington. When I looked at these, Bunch’s work just stood out. You could see he was being accepted … he was thick with everyone, yet his dispatches were incredibly hostile to slavery, to the mentality behind slavery, and eventually to the Confederacy.”

Bunch was also extraordinarily prescient. In the years leading up to secession, Charlestonians like Robert Barnwell Rhett, who had a controlling interest in the newspaper the Charleston Mercury, and Leonidas Spratt, owner of another newspaper called the Charleston Standard, whipped up a pro-slavery movement by playing to their fellow citizens’ worst instincts for white superiority, as well as their abiding fear that the slaves would rise up one night and slaughter them in their sleep. Rhett and Spratt, among others, argued for the re-opening of the trade in slaves from Africa, which had been outlawed for many years. There were various economic and labor reasons they put forward for doing so, but their core argument was one designed to absolve of guilt anyone who might think there was something wrong with slavery — and according to Dickey, there were many. “They were pushing the idea that slavery was really a good thing. It was the natural place of the Negro, it was the natural role of the white man, and if you were going to make that argument then you shouldn’t ban importing Africans even though everyone knew what happened on those slave ships,” Dickey says. “Bunch saw that was the key to undermining these people that he really did not like, and to distancing Great Britain [which was dependent on Southern cotton] from any support it might give to the South.”

Dickey completed some of his research in Charleston, but the bulk of Bunch’s letters are in England in the Duke of Norfolk’s Archives at Arundel Castle. Reading through the collection, and figuring out how what Bunch had written fit with all the other research he’d done, was like putting a huge, complicated puzzle together — with the resulting image being one that still won’t come completely into focus. “When you’re writing nonfiction about secret agents and spies, there are certain things we’ll never know,” Dickey says.

Even though he’s finished his book about Bunch, Dickey’s not finished researching or writing about the story. He recently penned a long essay in response to the removal of the Confederate flag from the S.C. Statehouse, and he says he will continue to try and learn more about Bunch and other figures who appear in Our Man in Charleston. And of course, there’s always Burton. “I’d still like to know what Burton was doing in the South in 1860,” he says jokingly. “Was he really just drunk and whoring or was he on to something?”