WITNESS IN BISHOP HILL

What if the only witness to a murder is in the early stages of Alzheimer’s disease? Detective Lieutenant Fred Lundquist and his second wife Joan, director of the senior center in Oliver, Indiana, are confronted with just this scenario when Fred’s mother, Helga, wanders from her home in the tiny Swedish-American hamlet of Bishop Hill, Illinois, and bumps smack into a big man whacking another man to death with a tree branch. While Fred, Joan, her college-age son Andrew, and Helga’s often napping husband Oscar grapple with Helga’s unreliable memory and tendency to roam and forget where she lives, the big man begins phoning the Lundquist home and whispering threats. His victim, meanwhile, has been identified as Gus Friberg, a career army man who’s the son of the Lundquist neighbors Nels, a heavy drinker, and Ingrid, the wife he’s browbeaten into compliance. As tiny Bishop Hills prepares for an old-fashioned Christmas with all the Swedish trimmings, two different women claim to be fiancées of the late Gus. One of them will wind up dead in a ravine, and Helga will drift in and out mentally and lose her way once more before Joan, in an unlikely “aha!” moment, identifies the murderer after a Christmas carol service.

A far testier Joan than usual (The Vanishing Violinist, 1999, etc.), though Fred and Andrew have settled into a companionable relationship. Lots of Swedish trinkets and foods on view, and even Swedish lyrics to sing along with, but the prize here is the gently effective interpretation of the Alzheimer’s scourge.