Michael Morpurgo is one of the UK's best-loved kids' authors and he's been talking to Newsround about his latest book, Shadow.
The former Children's Laureate has seen loads of his books get turned into stage plays and now Hollywood director Steven Spielberg is turning one of Michael's most famous books, War Horse, into a movie!
Shadow is based on the true story of a sniffer dog in Afghanistan, who went missing during an attack while out on patrol.
The soldiers thought the dog was dead, but 14 months later he shows up alive. The question is, who looked after him all that time?
Shadow is an imagined story about what happened to the sniffer dog. An Afghan boy called Aman befriends the dog when it turns up outside the cave where he lives.
When Aman's family flees the country and comes to England as asylum seekers, the dog Aman has called Shadow won't leave their side...
Why did you choose to set your new book in Afghanistan?
I've written a lot about war before but particularly wars that have been in the past. With these stories we know the outcome. But when we write about a war that's going on, it's much sharper because we're still full of anxiety about it.
You've written quite a few books about war - what's your interest in war?
Everyone is interested in war, in that people don't want it to happen. I'm much more interested in peace than in war but it's important to understand why we fight.
I grew up in 1943 [during World War II], I was a war baby. The first world I knew was a country that had been through a war. It affected me deeply.
Why should kids be interested in war?
It's important because kids know it's there, they watch TV, they know these things are going on. Books that kids read should be about what is going on in the world.
How did you research for the book?
I did a lot of research about soldiers in Afghanistan, and about Afghan people living in north Afghanistan. I found out about people living in caves in a place called Bamiyan. I researched those people in particular and decided that's where my family should come from.
I also researched a detention centre for asylum seekers called Yarl's Wood. It's the only place in the country where we still imprison children and I was very upset about that.
I visited Yarl's Wood. I didn't visit Afghanistan but I did talk to people who had been there.
Shadow is based on a dog - are you a dog lover?
Yes, we've had dogs in my family all my life until seven or eight years ago, when our beloved lurcher died and we felt we couldn't replace her. Now is the only time I've never a dog.
What's your favourite animal?
Elephants, but they're quite difficult to keep in your house!
I like their eyes - when you look into their eyes you know they're intelligent. I'm fascinated by how ancient they are and how they're prehistoric animals.
You have seven grandkids - do you test out your stories on them?
I don't test my stories on them anymore. I did a little with my children when I was younger. But I do test my stories out on school children. When I visit schools I read them what I've been writing.
I only tested out Shadow on my wife. She always says the same thing - it's very good, but it's not as good as War Horse.
War Horse is being made into a movie - how do you feel about that?
I feel very flattered that one of our great storytellers [Steven Spielberg] has chosen War Horse to make into a film. He's one of very few directors who can do it justice.
It's a very difficult story to tell. At the heart of the story there's an animal - the horse tells the story. There are no stars. It's about a war, the young people, and the animals with them. [Spielberg] will tell it brilliantly in the cinema.
What tips would you give kids who want to become writers?
Don't worry about writing a book or getting famous or making money. Just lead an interesting life.
Start writing two or three lines every day about something interesting that's happened to you. Go places, meet people - so you have lots to write about.
Read a lot of books, read everything - fill your head with stories, poems, facts.
What kids' book do you wish you had written?
Treasure Island. It's the first book I loved, when I was about nine, the greatest adventure story for boys. Robert Louis Stevenson is my writing hero.