The publication of Agatha Christie's notebooks will do nothing to reveal what made her tick, says Laura Thompson. Only her novels can do that. More than 30 years after her death, in January 1976, Agatha Christie is news once again. HarperCollins – with whom she first signed a three-book deal back in 1924 – is about to publish Agatha Christie's Secret Notebooks, a hefty volume that details, exhaustively, the contents of the 73 extant notebooks in which she sketched out plots for her detective fiction. In fact, there is nothing very "secret" about Christie's notebooks, which were first analysed by...