Newton crime writer William Landay has had nothing but good luck with his third novel, “Defending Jacob.’’ The legal drama - set, of all places, in sleepy Newton - debuted Jan. 31 in fourth place on The New York Times bestseller list for hardcover fiction. Now comes the movie deal: Warner Bros. has optioned the story for a feature film. Landay, 48, is a former assistant district attorney in Middlesex County whose novel centers around Andy Barber, an assistant district attorney in Middlesex County who lives in Newton. The plot twist is that his teenage son is accused of murder. “The whole reaction to the book has been surreal,’’ said Landay, who thinks George Clooney, Ben Affleck, or Matt Damon would be fine choices for the role of Barber. “It’s an interesting character to play. And that’s my unbiased opinion.’’Nicole Cammorata, Steve Greenlee, and Linda Matchan of the Globe staff contributed. Read the Names blog at www.boston.com/namesblog. Names can be reached at email@example.com or at 617-929-8253.