In the book, D'Artagnan doesn't actually become an official Musketeer until quite near the end, and we make quite a big thing about that. I won't give too much away, but when he finally does make it, they're not going to make it easy for him. That never changes.

You're always looking to make it a bit fresh. I want to make sure people are constantly surprised and interested, and we're always talking to the directors about that. It's a big challenge to find people that can do it.

The BBC came to me and they wanted to adapt the book [Three Musketeers] again, in the straightforward way, and I said no to that. I didn't want to do that. But what I did want to do was have a real look at the adventure genre because I thought it was ripe for reinvention.

You do see a few people and you are thinking of how that chemistry is going to work, but it's not really fair to put people who are auditioning together in a room. You have to make that judgement yourself, and that's partly where the casting director is so good. It was that blend that we were looking for.

You can use the fun of the genre, but I also really wanted to come at it from the point of view of some really complex characterization. There was a lot that I wanted it to do, and I wanted it to be fun. It's fun, but it's not simple fun.

On a simple level, you need directors who are good at action and can choreograph an action scene, but you need them to also have that sense of fun and that sense of movement and that ability to get the actors to really respond to the material in the way that you want them to. It's a very big thing.

Richelieu was a great statesman, and like all great statesman, he was a very ruthless man. He's not cruel. He just does what he has to do. And in his own mind, he's absolutely right.