Tuesday, July 20Big Sleep Books is bringing writer Walter Mosely to town in August for a reading and book-signing. We're letting you know now, so you have plenty of time to read his latest novel, Little Scarlet. Then, in August, you can ask Mosely probing questions and look smart. But you won't read it, will you? Instead you'll put it off, because it's summertime and you're too busy enjoying your vacation. Go ahead, take the easier route (lazy American!) and watch a movie based on one of Mosely's books. The Schlafly branch of the St. Louis Public Library (225 North Euclid Avenue; 314-367-4120) screens Devil in a Blue Dress at 6:30 p.m., and there's no admission charge. Take notes so that you can ask Mosely questions about Denzel's portrayal of Easy Rawlins and the subtext of the gardener. Oh, and you might want to take this down: Mosely's Always Outnumbered screens next Tuesday, July 27, at the same time. Just in case you forget this week.