It wasn't a simple task for George R.R. Martin to trust David Benioff and his fellow executive producer D.B Weiss with his masterwork "Game of Thrones." Benioff recalls the day they called the writer, and tried to get him on board him.

"We thought this was going to be a very tough sell, because we said, 'We love your books. We would love to adapt them. We don't think they can be movies,' " Benioff said. " 'We think maybe it can be an HBO series.' And we're waiting to hear the click, because, you know, there's just less money and for a novelist, it's less money in letting your book get optioned by HBO versus a movie studio."

But Martin was receptive to the idea.
 
"His response was, 'Well, that's the only way I've ever imagined this could be done, because the movie couldn't possibly do it. They'd have to cut everything out,' " said Benioff. It helped that Martin was a huge fan of HBO series like "Rome" and "Deadwood," added Benioff.

What followed was a 3-hour lunch of convincing.

"Right around the time of dessert, he hit us with this question, which I realized as soon as he asked it, this is the big test question," says Benioff. "And the question was: Who do you think John Snow's mother is? Which hadn't yet been revealed in the books."

John Snow was a key character, and Benioff guessed correctly.

"He was quiet for a long time, stroking his beard. And he said, yeah, you got it. And from that point on, we were partners."

Watch George RR Martin about how his books came to be adapted on HBO. He also talks about the readers spoiling the story for the show viewers and the two different types of readers he has now for his book series.