Thorn is back, and he’s madder than ever.Like many fans of Florida crime fiction, I’ve been addicted to James W. Hall’s series of propulsive, elegantly written novels about Thorn, the tough Key Largo loner who insists he’s a misanthrope but somehow gets drawn into protecting the vulnerable no matter how dangerous it might be.From Under Cover of Daylight , published in 1987, to The Big Finish in 2014, Hall wrote 14 novels featuring Thorn, winning the Edgar and Shamus awards along the way. He has also published seven other novels, four books of poetry, two short story collections and two works of nonfiction. An Eckerd College alum, Hall became a professor in the creative writing program at Florida International University, from which he recently retired after 40 years. He now lives in North Carolina, but Thorn still lives in his quirky old house on Key Largo.When first we see him in Bad Axe , the 15th book in the series, Thorn is basking in the heady stage of a new romantic interest. (His hermit tendencies have often been suspended for attractive women.) The new squeeze is Sofia, a lovely young bartender, and they’ve just come home from a trip on Thorn’s boat that included a visit to her Cuban refugee family in Key West.Their blissful interlude is interrupted by Thorn’s best friend, Sugarman, a private investigator who is the laid-back, gregarious, methodical yin to Thorn’s aggressive yang.Sugarman is delivering a request for assistance from their friend Bobby Tennyson, who has a wild story to tell. During the Vietnam War, Tennyson was stationed on Johnston Atoll, an island dumping ground for various military chemical and radioactive weapons. One day, a couple of strangers, a muscle-bound guy and a seductive young woman, sailed in on a boat made to look like an old Chinese junk. The woman, Savannah, turned out to be the daughter of the post’s commanding officer. After the pair sailed away, two dozen M23 land mines loaded with VX nerve agent, “the deadliest gas in the U.S. arsenal,” were missing.The mines were never found. But now, nearly 50 years later, Tennyson has gotten an ominous text from a blocked number: “M23′s stolen. Bad things are coming.” And he fears those bad things have started. He shows them a newspaper story about the mysterious deaths of five undocumented immigrants who died when a truck exploded near the border with Mexico — deaths that show all the signs of having been caused by an M23.Can Thorn and Sugarman help him find out what’s happening?Thorn is reluctant to leave his love nest, but Tennyson once saved his life in a freak fishing accident. So it isn’t long before Tennyson, who’s a pilot, is flying Thorn and Sofia to Tucson while Sugarman dives into internet searches.By the time they get to Tucson, a similar explosion has killed another 11 immigrants near the small border town of Frontera. Thorn and his friends discover that blast had a miraculous survivor, a 15-year-old Honduran girl named Dulce Mérida. But she’s so traumatized by the explosion, which killed her mother, that she isn’t talking.The local sheriff has put her in hiding, fearing the killers will come back to take out the only witness to their crime. They do, but Dulce escapes yet again, thanks to Thorn, with whom she forms a precarious bond of trust.Hall’s readers know that once Thorn is on a case, he doesn’t stop. This case will lead him far out of his Florida comfort zone, though, not only to the vast Arizona desert but to the little town in Michigan that gives the book its title.Along the way, secrets will be revealed about Tennyson, about Savannah, and about almost every other character. Thorn and Sugarman will try to protect Dulce while tracking down what has happened to the land mines and who is using them now.The trail leads to a disturbingly widespread net of white supremacists. They range from those whose most overt act is spewing racial bigotry in dark web chatrooms to monsters who capture, rape and kill immigrants for sport; perhaps the most lethal are the ones who have decided all the true believers are just suckers whose money they can grab.The harder they fight, the angrier Thorn gets. It all leads to a hold-your-breath (in more ways than one) finale that will make you glad Thorn is back. Bad Axe By James W. HallIndependent Publisher, 287 pages, $14.99 Times Festival of Reading James W. Hall will be a featured author at the virtual Tampa Bay Times Festival of Reading , Nov. 12-14. If you have a question for Hall, email it with the subject line “Festival author question” to email@example.com .