World War I raged from 1914 to 1918. It killed many thousands and left countless others with emotional and mental scars that were little understood at the time—a terrible legacy of shock and mental disability that affected many of those who fought,  sometimes for the rest of their lives.

Charles Todd’s war novels have explored those lasting scars in two series, his Ian Rutledge mysteries and, beginning in 2010, a newer series featuring Bess Crawford, a World War I nurse.

In this ninth installment in his Bess Crawford series, A Casualty of War, the mother-son writing team known collectively as Todd has provided an authentic look at the visceral horrors of trench warfare, as they set readers down in a makeshift medical facility, or “forward aid station,” near the front lines. Bess has been assigned there near the end of the war, after another nurse has attempted suicide due to the high stress level at the facility.

Bess soon makes the acquaintance of one Captain Travis—first as a soldier about to rejoin his regiment, and soon after as a gravely wounded soldier himself; one who insists, moreover, that his distant cousin has intentionally tried to murder him on the battlefield. Trouble is, that cousin was killed in battle weeks before Travis was himself wounded. For his insistence on what took place, the captain is transferred to a mental facility, where his condition soon deteriorates.

Bess appears to be the only person who believes the captain may be telling the truth, and following the armistice she sets out to make sense of his claim and hopefully prove him sane. It won’t take readers long to discover that where there are two branches of a family, there’s often a will in dispute. Bess and her friend Simon set out to begin a search within the fold of the Travis family—a dangerous undertaking that involves a whole community as well as a number of family skeletons.

The authors deftly explore the early ways in which the medical community as well as families and loved ones try to understand what we now know of as post-traumatic stress disorder. A Casualty of War brings into sharp focus an era that thrust the world squarely into the 20th century.

It’s best to leave your revolutionary fervor behind and just give in to the beautiful and opulent settings that blanket Tasha Alexander’s new mystery, Death in St. Petersburg. Set in that storied city in the early 1900s, before the cataclysm of 1917, Alexander’s novel captures St. Petersburg at the peak of its glitz and aristocratic splendor. The enchanted winter setting benefits from lines here and there from poet and Russian literary genius Alexander Pushkin, as this one that captures the atmosphere: “I love thy winters bleak and harsh; / Thy stirless air fast bound by frosts; / The flight of sledge o'er Neva wide, / That glows the cheeks of maidens gay. / I love the noise and chat of balls; / A banquet free from wife’s control, / Where goblets foam, and bright blue flame / Darts round the brimming punch-bowl’s edge.”

Sleuth Lady Emily, here in her 12th outing in Alexander’s popular series, is in Russia with her debonair and attractive husband, Colin. They investigate the tragic murder of prima ballerina Nemetseva, found outside the Mariinsky Theatre after her premiere performance as Odette/Odile in “Swan Lake.”

The book takes readers behind the scenes with a crash course in ballet, describing the beauty and cruelty of the unforgiving, competitive life of a top-level ballet dancer in Russia’s storied and revered Imperial Ballet.

The book cleverly balances flashbacks with Lady Emily’s current day, presenting the fascinating backstory of young Irusya (Nemetseva) and Katenka, young dancers in the corps de ballet, whose lives become intertwined over the years, right up to the fatal event, as the flashbacks catch up to the present day. Irusya’s brother, Lev, and his revolutionary circle of friends contrast with the aristocrats living sheltered lives in precarious comfort at their soirees and balls, while princes bestow expensive favors on their favored ballerinas, who remain a lower class . . . all setting the stage for events to come.

But it’s St. Petersburg that stars in this show, as we accompany Lady Emily and her husband through a brilliant Russian winter, where horse-drawn sledges draw their muffed and ermine-swathed occupants over the sparkling snows to the hush of a theater at opening; where glittering Fabergé jewels are trinkets for the rich; and where a ghostly ballerina appears in the city, bearing marks of her murder, and then disappears into the snowy landscape.