Another crackling exchange from The Maltese Falcon. Part of this is in the film as well, although sometimes the dialogue goes so fast on the big screen it's hard to catch every twist and punch. On the page, though, you can relish every clever turn.
In this scene (it's impossible not to think of them as scenes in a book as cinematic as this one), Sam Spade has come in to see District Attorney Bryan at his request. Bryan wants to know what Sam knows. And we're off to the races:
..."Who killed Thursby?"
Spade said: "I don't know."
Bryan rubbed his black eyeglass-ribbon between thumb and fingers and said knowingly: "Perhaps you don't, but you certainly could make an excellent guess."
"Maybe, but I wouldn't."
The District Attorney raised his eyebrows.
"I wouldn't," Spade repeated. He was serene. "My guess might be excellent, or it might be crummy, but Mrs. Spade didn't raise any children dippy enough to make guesses in front of a district attorney, an assistant district attorney, and a stenographer."
"Why shouldn't you, if you've nothing to conceal?"
"Everybody," Spade responded mildly, "has something to conceal."
"And you have--?"
"My guesses, for one thing."
Nobody, but nobody, does this quite like Dashiell Hammet.