The setting is the Blitz of World War II, England enduring nightly bombing raids. While the royal family feels it a personal duty to lend moral support to their suffering subjects, concern for the well-being of the royal daughters prompts the king and queen to remove the princesses from the country until they can safely return. A secret process ensues, one where even the girls' destination is kept private, the world at war a particularly dangerous place for royal children.

Author Benjamin Black, aka prize-winning literary author John Banville, draws his readers to Ireland, where the 10- and 14-year-old girls are spirited to a countryside estate, there to become houseguests in Clonmillis Hall, the rather Gothic estate of Sir William Ormonde, Duke of Edenmore. Sir William, unaccustomed to children yet devotedly patriotic, depends entirely on his longtime housekeeper, Mrs. Ohanlon, to handle all aspects of the oversight of Ellen (the older girl) and Mary (younger). The entourage arrives a bit prematurely, flustering Sir William and his irascible but efficient housekeeper. The entire group of guests consists of Celia Nashe (MI5), Detective Garda Strafford and British Embassy official Richard Lascelles, the putative caretakers of little "Mary and Ellen". All are meant to flow seamlessly into Sir William's rather moldy household.

In spite of the isolation of Clonmillis Hall and the intense secrecy surrounding the "visitors", neutral Ireland is not without its political skullduggery and national resentments. That includes its own homegrown enmities, some residential rivalries inspired by a loss of family to the English during the War of Independence. This natural distrust, once combined with the numbing boredom of day-to-day existence in a gloomy manor and the mischievous activities of the youngest houseguest, foments a quietly percolating discontent, eventually a plot that draws attention to the true identity of the visitors, and a violent outburst that leaves a few ill-starred combatants dead.

With his usual mastery of plot and characters, Black spins rumor into whole cloth, perfectly capturing an estate's hierarchy temporarily invaded by five strangers. The three adults hide their personal responsibilities as temporary protectors of their precious and precocious cargo, unable to catch one young culprit before a dangerous drama has begun. The result is a mix of good intentions, petty piques and long-nurtured resentments complicated by clandestine romance, an ill-informed perception of propriety and the meddling of a bored young princess too long protected from real-world consequences.

While England withstands the brutal air attacks of the enemy, quite another deadly contretemps builds in the Irish countryside as passionate and dangerous as the war "the secret visitors" were intended to escape. It's a reminder that chaos can creep into the smallest of spaces, inflicting its damage when the hour is ripe.