Mary Higgins Clark, the bestselling author who has written dozens of page turners, has two rules when beginning to write a suspense thriller.
"You have to know who did it ... and why he or she did it," the author told CNBC's "On the Money" in an interview. Yet while she always knows the culprit, "I don't know the final scene when I start the first. I have to figure that one out."
In a prolific writing career, Higgins Clark has penned more than 50 books, selling more than 100 million copies in the U.S. alone. As for the actual writing, she says she gets help from the characters she creates, and the people in her stories.
"Once I know the people, they tell me where to go now and what's the next," Higgins Clark said. "I mean, I can be writing and a character will say, 'I don't belong in this scene, I'm getting out.' And that's when writing is fun."