The Sarah Jane Adventures see one of The Doctor's old companions fighting aliens with the help of her 13-year-old neighbour, Maria, and her friends.
Sarah Jane's an investigative journalist who first appeared in Doctor Who in the 1970s.
Now she's got her own series with her own companions - Maria, Luke and Clyde. Newsround met the young stars to chat about their new roles.
You can watch the full interviews on our Broadband player - click on Launch Newsround Player on our front page and it's under interviews
Yasmin Paige, who plays Sarah Jane's neighbour Maria, said the series was action-packed: "There's lots of running, lots of chasing and lots of amazing monsters coming up."
But what's her character like?
"She's very intelligent, very funny, quite witty, strong minded," said Yasmin.
"She's sort of like a miniature Sarah Jane and that's why they get on so well.
"Clyde is my favourite character because he's so relaxed, so funny and also a really nice guy underneath."
Clyde is played by Daniel Anthony who admits his character is very popular with the girls.
"You first meet him in the school and he's basically a bit nosey, a bit of a cocky kid. All the girls love him apparently."
But Daniel said he'd never seen anything like the creepy aliens in the show before.
"They're pretty cool though, all the prosthetics and the stuff they do is amazing.
"The Slitheen's heads are done with remote controls so they can frown and move their mouths and speak at you - they're pretty creepy."
At 19 years old, Daniel said he thought it would be weird working with actors who were much younger than him, but he needn't have worried.
He said: "Yas and Tom are like 14, 15 so I thought it would be really strange, but we get on like a house on fire.
"I'm a big kid anyway so I just love prancing around, it's a laugh."
Tom Knight plays the character of Luke, who's a created human.
But what does that mean? Tom told us: "He was made by aliens. He's not an alien himself but apparently he's the perfect child.
"He was given the memory and understanding of thousands of people which is pretty sweet."
Tom said he'd had a great time on set but still had to find time to do his school work.
"I have to get in at least three hours of it every day. When I come off set I'll have to sit down in this room and I'll have to do the work that I got from school.
"It's a bit lonely. It's different to school because at school you've got all your friends there and it's a laugh but when you're doing tutoring you've got to sit there and buckle down."
Maybe he could get the Slitheens to help. Tom said he found himself in a room with three of the aliens one day after the cameras had stopped filming and they were still pretty scary.
"There was these three big green people in big old suits and when you're standing there in front of them you can almost begin to believe that they're sort of real and it can get to you a little bit."