Gideon Stoltz, sheriff of (the fictional) Colerain County, Pennsylvania, in 1836, faces long odds in solving his latest case. He suffers headaches and memory loss because he fell off his horse and hit his head. His deputy does his best to cover for him, but Gideon’s boss, an arrogant attorney, openly hopes the voters will turn the young sheriff out of office come autumn. At only twenty-three, Gideon fears for his future, but the present looks pretty dreadful too. His wife, True, locked in grief over their young son’s death from influenza, won’t speak to him or even stir from bed.

But that’s just for starters. A woman said to be a witch has been found dead in Sinking Valley, a farm district more than a day’s ride from Adamant, the town where Gideon lives, and he’s not sure he can manage an extended trip, given his physical ailments. He’s hoping that the rumors of suicide prove true, and that he can investigate briefly and return home.

However, he not only knew the dead woman, Rebecca Kreidler, he has the strongest impression that he visited her on or about the day she died. Could he have killed her? Could he have taken her to bed, even, for, like many men who knew Rebecca, he lusted after her? The notion fills him with shame.

What’s more, when Gideon begins questioning the good folk of Sinking Valley, he uncovers complexities that challenge a verdict of suicide. Rebecca’s beauty aroused desire and envy, and her knowledge of medicinal plants invited both gratitude for her cures and suspicion of witchcraft. Then again, her past preceded her, for a woman who kills her husband — no matter how violent or abusive — has marked herself as an outcast, and her three years in the penitentiary is not considered adequate expiation.

This ingenious framework, and the facets Fergus gives it, make Nighthawk’s Wing compelling reading. Gideon Stoltz is a man first and a detective second, and though the two naturally intertwine, the narrative offers much more than a whodunit — luckily, for reasons I’ll get to. Not only do Gideon’s cognitive difficulties and the various reactions to them provide a touching, unusual background in a mystery, the social atmosphere places the narrative firmly in the central Pennsylvania soil.

Like many people in Sinking Valley, Gideon’s of German extraction, or, as commonly called, “Dutch,” apparently a corruption of the German word Deitsch, how they describe themselves. Much hated and maligned for being different, they occupy a social position that marks the story. With skillful economy, Fergus deploys the animosity to effect, tracing its roots and consequences, and since Rebecca was Deitsch, Gideon must take that into account.

Another pleasure of Nighthawk’s Wing involves the vivid, very much lived-in picture of early nineteenth-century rural American life. Fergus shows us crafts, like grinding and resetting a millstone, or a blacksmith shoeing a horse, and recounts herbal lore and depicts burial customs. Such authenticity extends to various mounted creatures, for riding a beast requires particular skills or physical heft, and either you have them, or you don’t:

The narrative from Rebecca’s point of view works less well, I think. I believe her portrayal as a psychotic — one of her delusions gives the book its title — but by going back in time to let the now-dead speak feels like a copout, telling us what Gideon couldn’t possibly know. That may not bother other readers; and I may also be alone in my dislike of the supernatural elements that play a strong role, especially toward the end.

But I wonder whether other readers will agree with me that Fergus has tipped his hand concerning the killer’s identity, which I latched onto because of how mystery novels are typically put together. I don’t want to say more, for fear of giving too much away, but despite this drawback, I do believe that Nighthawk’s Wing deserves its audience. I congratulate Fergus for the loving care with which he re-creates the time and place and crafts his characters. If you’re like me, that will justify reading the novel. ( )