Integral to most crime tales is the unearthing of concealed and unfavorable facts about suspected malefactors. But the mother-son duo who write under the nom de plume "Charles Todd" are particularly adept, in their historical novels featuring Scotland Yard Inspector Ian Rutledge, at exploiting painful secrets as tools in developing both character and plot. It's rare, in a Todd tale, that even the innocent should escape unscathed. The authors demonstrate their skills once more in A Cold Treachery, which sends the shell-shocked and lonely Rutledge to probe the winter massacre of a sheep-farming family in northern England, at the same time as he searches for the missing and only witness to that chilling savagery. "It was beyond comprehension," we're told of the December 1919 violence, near the rustic Lake District town of Urskdale, that left Gerald and Grace Elcott and three of their progeny shot to death. A fourth child, 10-year-old Josh Robinson, is nowhere to be found. He's thought to have fled from the scene, only to have perished in a recent blizzard. Coming off the grim proceedings recalled in A Fearsome Doubt, Rutledge--shackled as always to the nattering ghost of Hamish MacLeod, a Scotsman he'd ordered executed on a World War I battlefield--must determine whether the murderer was a passing stranger, or a local who'd previously concealed his or her aptitude for barbarity--and might kill again. Gerald Elcott's less-successful brother, Paul, has ample motive (he's next in line to inherit their clan's farm), as does Grace's sister, Janet Ashton, who just happens to arrive in Urskdale with a gun in hand (supposedly to protect her sibling from Paul's anger). Yet there's another, more frightening possibility--that Josh, Gerald's stepson, upset by the breakup of his parents, committed these atrocities. Desperate for clues, and with his impatient superior threatening to replace him on this case, Rutledge still can't claim to know who, or what, was behind the carnage. After their disappointing standalone, The Murder Stone, it's a relief to see the Todd pair return to the "gloomy, defeated and exhausted" postwar England of Ian Rutledge, where no end of dire dramas appear to lurk. Like its half-dozen predecessors, stretching back to A Test of Wills, A Cold Treachery satisfies with its copious period details, characters traumatized by fate and failures, and a bedeviled young protagonist who must solve other people's problems before his own. And even as Hamish seems here to slip further into the background, there's finally the prospect of Rutledge finding companionship of a more corporeal sort. --J. Kingston Pierce