Once, after a row with her husband, the mystery writer Agatha Christie went missing from her home for a few days without telling anyone where she had gone. For a brief time the press speculated that she might have been kidnapped, falling victim to the kind of plot development Christie might have used in one of her stories. This was the starting point for the movie 'The Lady Vanishes', and here it is dredged up again. Using scraps of the writer's own words, reported and written, this drama-documentary sets out to explore the inner workings of Christie's mind and reveal what was really going on when she did her famous bunk. Sadly the result is painfully pedestrian. The 1930s period hairstyles and clothes are all done as well as you would expect from the BBC; but an audacious lack of pace, the trite psychological 'insights' offered - insights that never really add up to anything - and the frankly dull performance from Olivia Williams as the young Christie (Anna Massie makes a much better fist of the elderly version) make for a very long 90 minutes indeed. One reads a lot about 'stillness' in front of the camera being important when acting for the screen, but Williams's resolute lack of expression acts like a lead lining. She has in the past been described as an actress (sorry, actor) people just like to look at, but if so, she has been trading on this advantage for too long. Earlier, in the same occasional series, the BBC did a similar drama documentary on George Orwell, "in his own words". That film was extremely good. This effort is not remotely in the same league.