Agatha Christie was over 80 when she wrote her last two books, and Dame Agatha had clearly lost her touch. I remember reading Postern of Fate (her final novel) on vacation when I was 16, and thinking that it just didn't add up. In 2009, a pair of Toronto academics analyzed several of her books, and determined that by the time she wrote her penultimate book, Elephants Can Remember, she may have been suffering from Alzheimer's Disease. The authors also suspect that Christie may have realized that something was wrong.
Elephants Can Remember is a murder in retrospect, but one in which the past is shrouded in fog. A domineering middle-aged woman confronts Ariadne Oliver after a literary luncheon and asks about the parents of one of Mrs. Oliver's goddaughters. Did Celia Ravenscroft's mother murder her husband and then commit suicide, or was it the other way around? Mrs. Oliver can barely remember Celia - she's one of a dozen or more godchildren - but she's more troubled by the fact that she's forgotten the death of her friend, Celia's mother. She consults with Hercule Poirot, and the two decide to "hunt elephants" with Mrs. Oliver hunting down former hairdressers, maids and nannies and Poirot interviewing retired policemen and Swiss au pairs. The answer is the sort of twist more worthy of an afternoon soap opera than a canonical mystery writer, but she supports the conclusion and ties it up reasonably well. The rest of the novel, though, is a bit messy - a few characters appear and disappear without warning, the past scenes are indistinctly written, and while Christie has clearly set the book in 1971, it's a 1971 set barely fifteen years after the glory years of the British Empire.
Ian Lancashire, one of the Toronto researchers, saw a kind of heroism in Elephants Can Remember, and I agree. Her avatar can't seem to remember where she put things and people who were important to her twenty years ago may as well not exist (although she has very clear memories of her own early childhood). Mrs. Oliver fights the fog, though, and learns what truly happened to Celia's parents. It's almost as if her creator were fighting to escape the mist which may have been clouding her formerly sharp mind.