"Turtle Diary" tells a preposterous -- even silly -- story but is saved by great performances, an evocative score, and consistent good humor. There has never been a more commanding screen presence than Glenda Jackson. What a shame it is that she has deprived us of her formidable talent in order to become a minor league politician. Ben Kingsley is also wonderful. `Turtle Diary' calls for patience but those who exercise it will be well rewarded. 7 out of 10.