War - especially the politics of war - changes everything in a historical mystery. Ever since Anne Perry took her stalwart working-class hero, Thomas Pitt, off the streets of Victorian London and elevated this former police detective to a post in secret intelligence, the books in this series have become more overtly political, making them more exciting, but, frankly, not as much fun. Pitt's well-born wife and canny sleuthing partner, Charlotte, says as much in TREASON AT LISSON GROVE (Ballantine, $26). Thinking back to the days when her husband still needed her help to negotiate the closed ranks of high society, Charlotte acknowledges the danger involved in those early cases of scandalous domestic passions and deplorable social evils. "But she had loved the adventure of both heart and mind, the cause for which to fight." Charlotte gets to taste danger again when she skips off to Dublin to infiltrate a group of Irish nationalists who may have had a hand in a plot against Victor Narraway, Pitt's boss at the Special Branch before he was ousted by a personal enemy and possible traitor. Posing as Narraway's sister, Charlotte blooms in the lively society of the Irish capital, stimulated by "the vitality in the air, the energy of emotion in the gestures." And Narraway's forbidden love for her intensifies the thrill of this daring escapade. Pitt, meanwhile, has been lured away to France in pursuit of a fugitive anarchist, a ploy that keeps him from helping Narraway and distracts him from a more immediate threat at home. A stern but compassionate man, Pitt is sensitive to the widespread social injustice behind the cries for revolution heard throughout Europe in 1895. But bringing down the English government is something else again, and when Pitt swings into action the narrative accelerates accordingly. Perry writes with great urgency about the desperate actions of people who believe they're fighting for a just cause. But, as Narraway points out, political anarchists aren't social reformers. "They're fanatic," he observes. "It's the new religion, with all the fire and evangelism of a holy cause." Anyone can pick out these zealots in a mob on the waterfront. Perry's skill lies in her ability to place one of them across the table from you at a tea party, graciously handing you a plate of cucumber sandwiches. World War II has been over for almost 10 years in FIELD GRAY (Marian Wood/Putnam, $26.95), the darkest and most disturbing of Philip Kerr's novels featuring Bernie Gunther, the former German police officer and wiseguy private eye of his Berlin Noir trilogy. Bernie is living the lazy life in Cuba in 1954, doing this and that for the gangster Meyer Lansky, when a chance run-in with the American Navy sends him first to Guantánamo and then to Landsberg Prison in West Germany, where he's roughed up by American interrogators and grilled about his wartime relationship with Erich Mielke, soon to take charge of the East German Stasi. Anxious to distance himself from the war criminals stockpiled at Landsberg, Bernie takes his interrogators back to 1930, when a humanitarian impulse led him to save Mielke's life in Berlin. But the young Communist repaid the favor by killing two policemen, sending Bernie on a vengeance mission that lasted throughout the war. Thanks to his examiners, Bernie is forced to reflect on horrific events that Kerr seems to have culled from historical sources. But Bernie's cynical, completely twisted idea of payback is brilliantly in character. Although he never served in any man's army during World War II, John Russell has always been in the thick of things in David Downing's powerful historical novels set largely in Berlin. POTSDAM STATION (Soho Crime, $25) finds this well-traveled Anglo-American journalist in Moscow in the spring of 1945, angling for a way to get back into Berlin, where his German girlfriend is still trapped, before the Reich falls and the Red Army starts exacting its revenge on the surviving populace - starting with the women. Russell gets his pass; but it's not free. He must guide an expedition to Berlin on a secret hunt for documents from the German atomic research program. Downing provides no platform for debate in this unsentimental novel, leaving his hero to ponder the ethics of his pragmatic choices while surveying the groundlevel horrors to be seen in Berlin. The assaults on the ear are no less shocking, from the screams of women in the night to the appalling silence at the end of it all. Amateur detectives don't usually interrupt their duties to go tearing off to war. But Clare Fergusson, the Episcopal priest in Julia Spencer-Fleming's unconventional mysteries, has always been a genre rule breaker, so it makes sense that this former military pilot would sign up for another tour of duty in Iraq. Clare is already back in her Adirondack parish in ONE WAS A SOLDIER (Minotaur/Thomas Dunne, $24.99), but like a lot of returning vets she finds herself with a combat-related problem, a dependence on pills and liquor. Turning to a support group, she meets other troubled soldiers, including one who commits suicide. At least, that's what Clare's fiancé, the chief of police, calls it, but Clare has her doubts. Spencer-Fleming knows her craft, which lends authority to the subsequent investigation. But it's character that really counts here, and nothing becomes Clare's character more than her deepening sensitivity to the suffering of her fellow soldiers. Anne Perry's workingclass hero, Thomas Pitt, now has a post in secret intelligence in Victorian London.