Torchwood: Miracle Day - BBC Press pack

Jack's relationship with Gwen is – he is very fond of her, but it's more than that. He is very protective of her. Gwen was always the heart of the group, but she has evolved herself. She's still the heart, but now is a bit of the muscle. And Jack, through the process of them being together, has taught her the art of fighting, gun slinging and all that stuff. She has come a very long way. But their relationship is funny, because it's almost like a brother and sister relationship and it's almost like a husband and wife relationship. But there's nothing sexual between them, it's the type of thing where she might finish one of his sentences or vice versa because they know each other so well. And, between Jack and Gwen, if they're in a sticky situation, all it needs is a look from one of them and then they know exactly what they're thinking.

At the end of Children Of Earth, both Jack and Gwen went their separate ways. Jack went off somewhere and Gwen moved to a very quiet part of the country into hiding because she was being hunted. She's been wanted because she's the last remaining member of Torchwood. She goes away and has a baby and lives there with her husband, and they've got quite a perfect, chocolate box kind of cottage, and it's idyllic.

But she is so bored. She's in limbo land and she never switches off. She's constantly in Torchwood mode and always on alert. So when this particular event happens and Captain Jack turns up, he couldn't have turned up at a better time for her, because she was lost.

I wouldn't describe Rex as arrogant but I think he's certainly set in his ways. There's a certain amount of edge to him. I think he's determined and strong and focused. And I think once he has it set in his mind that he wants to do something, that's what he goes out and does. He just goes out and makes it happen, He's very much a black or white person – he's not a grey area guy.

When Rex first meets Captain Jack, they just flat out don't like each other. John's a great guy in person – really funny – loves life. And he's always singing and dancing around and saying crazy things, so I just love the guy. But our characters, definitely in the beginning, clash, there's no question about that. We definitely have different approaches to things. And I haven't figured him out yet.

Coming to the US for Torchwood (the organisation) is like another case. They've dealt with galaxies and universes, so another country is not that big of a deal. It is, however, a big deal for Gwen. She's separated from her husband and from her child. She's arrested and taken to America, so it's heartbreaking on that level. But for Jack, he hits the ground running. For many years Torchwood (the series) has had an American actor in the lead role, so in that sense it feels entirely natural. For the show to hit America, I think it's a new start without being a reboot. That's what's exciting about it. This is simply a new horizon. We have different producing partners, and it has added a new influx of imagination, and frankly, a bigger budget as well.

If you haven't watched Torchwood before, the first important thing to say is – don't be afraid. You don't have to know anything about the show or its history. Everything is explained from the beginning. In that way, it's a completely welcoming new show for a brand new audience. And you should watch because it should be a lot of fun. It's a thriller that is properly answered in 10 episodes. It's not the type of show where you have to hang on for five years and at the end of that you're weeping trying to understand who everyone is and how stories have properly been tied together.