"You've introduced characters in the last five pages who weren't in the book before!" words spoken by Truman Capote in the movie "Murder By Death". Have you ever seen this movie?
"I was wearing a disguise, in a disguise, in a disguise!"
If you want to watch a funny movie with clever dialogue that keeps you guessing all the way to the end, you need to watch this movie. Classic actors like Alec Guiness, Nancy Walker, Peter Falk, James Coco, and many more, are in this movie. The mix of accents and stereotypical characters remind you of days gone by, old black and white movies, and murder mysteries that seem almost too obvious to miss.
While I was watching it, I was reminded of movies like the Maltese Falcon and To Have and Have Not. Peter Falk did a great job imitating Humphrey Bogart as he played a detective. He even used some of the classic lines we remember so well. "The last time I trusted a dame was in Paris in 1940. She said she was going out to get a bottle of wine. Two hours later the Germans marched into France." The allusion to Casablanca can't help but make you laugh. Here's another line - "I don't get it. First they steal the body and leave the clothes, then they take the clothes and leave the body behind. Who would do a thing like that?"
Dialogue can tell you so much about a character. The way they ask questions or respond to others can tell you more than ten sentences of description. When you write your story, you have to be careful how you show, not tell a story. The use of dialogue is a great way to do this. My advice - watch some old movies that do it really well. Many of them are based on novels that were bestsellers. Others are just the result of fantastic screenwriting. Whatever the case, if you need help writing dialogue, listen to the experts.
When Don Corleone says "I'll make him an offer he can't refuse", we know exactly what kind of man he is.
It could be, that like Captain says in Cool Hand Luke "Looks like we've got here is a failure to communicate." So think about what your characters say as not just something to say, but a keyhole view into your character's soul.