"When the doorbell rings three in the morning it's never good news." 

The quote could be taken from Ian Fleming, but in fact it is the opening line of Stormbreaker, the first novel in Anthony Horowitz's globally successful Alex Rider series. The echo of Fleming is notable for two reasons: firstly, Alex is a teenage spy who's saved the world nearly as many times as James Bond (13 times and counting).

Secondly, the stories are played totally straight: Horowitz saw himself as writing "an adult book for kids" and Alex's world is no less dangerous or brutal than Bond's. The stakes are high -- Stormbreaker involves the attempted genocide of British schoolchildren, and that's one of the more grounded entries in that there isn't a nuclear bomb -- and the body count higher still.  

Since Stormbreaker's publication at the turn of the millennium, more than 20 million Alex Rider books have been sold around the world. Readers have joined Alex in battling fanatical Russian Generals, insane pop superstars, vengeful clones, mysterious assassins and a nefarious organisation known as SCORPIA. He's been killed off, resurrected and launched into space. He's faced down sharks, bulls, jelly fish and feathered serpents. His school work has suffered something rotten.   

Last year, Alex came to Amazon with an acclaimed TV adaptation of the novel Point Blanc (originally intended to be the first books as well). It's clear the teenage superspy isn't going anywhere. We sat down with Horowitz to discuss the series that has engrossed several generations of teenagers, and will do for many generations to come. Remember: you're never too young to die.   

What inspired Alex Rider? 

It was inspired by a thought I had a very long time ago watching James Bond movies at a time when Roger Moore was playing Bond. By the time he made A View To A Kill, he was 57 years old, which is far too old to be Bond. And the thought occurred to me, 'why can't Bond be a teenager?'

That lightbulb moment stayed with me for about ten, 20 years before I finally went out and wrote Stormbreaker, the first book in the series, but that's where it all began. And I should say that my aim from day one was to make Alex as unlike Bond as possible. I don't see him as a junior James Bond, but that was the inspiration.

Were you surprised nobody had done something similar with a teenage spy?

Well, looking back on the world of children's books in the year 2000, when I wrote Stormbreaker, it's very interesting in that there was a sort of a before and an after, and one of the good things about Alex Rider was thinking about him at exactly the right moment.

There weren't young spies, there weren't young detectives; children's books still belonged very much in the children's world. And the idea of taking the child and putting that child into an adult world was something that happened around that time. Everything changed. I think we went from the Roald Dahl children's books to Harry Potter, J.K. Rowling, which was exploding at that time.

It was a new generation of children's authors: Malorie Blackman, Philip Pullman, Michael Morpurgo, to an extent, Darren Shan, certainly, who were more sophisticated and more adult, less patronising. And I was part of that.

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Did you set yourself any rules when you wrote Stormbreaker?

I don't exactly set myself rules. One very big difference with Stormbreaker: it was the first children's book I wrote that refused to behave like a children's book.

Alex didn't have a fun adventure. He wasn't having a good time. He didn't even want to be a hero. In most children's books, the kids enjoyed the adventure, Alex didn't really. And the fact that he was an orphan wasn't just sort of a happenstance and for the plot, it was something that actually preyed on his mind -- the unhappiness of not knowing your parents. So it was a slightly more serious work than anything I'd done before.

I always say that it was defined by the very first sentence. "When the doorbell rings three in the morning it's never good news" is not a classic opening for a children's book. It is much more an opening for an adult book. And that was what I always saw it as: an adult book for kids.

Was there a particular scene or set-piece that gave you entry into Alex's world?

The snowboard chase at the end of Point Blanc was one of the very first things I thought up. Point Blanc was going to be the first book, but since the plot was so fantastical -- with clones and a slight sci-fi edge -- it wasn’t the right one to start with. So I postponed it.

But that sort of scene where you take the children's world or the teenage world -- James Bond can't really snowball. Adults on a snowboard, it's a little bit embarrassing. So the idea of taking teenage things, teenage bicycles, teenage gadgets, teenage accoutrements like a snowboard, and then using them in the service of spy novels, was very much sort of what the books are going to be about. And so that, I guess, is an image that came with me very early.

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How much of a character could you make Alex? Presumably the reader should be able to insert themselves in his place?

Well, on the one hand, I'm trying to be universal. I've always thought this with a hero in a children's book -- James Bond is a good example, there is a certain universality to James Bond which is why he can be played by all those actors from Sean Connery to Daniel Craig. He can keep changing it. He's also always somehow James Bond. He's actually a mythological figure as much as a human being. And I think there's an element of that in Alex, too.

When a child reads Alex Rider, the idea is that the child can be Alex Rider. So therefore you don't want the kid to be too extreme. But that said, I think he is a strong character and he certainly developed over the 13 or 14 books I've written about him.

What was the experience writing this book that became a massive, almost overnight success?

It may look like an overnight success, but for me it was a night that lasted about 15 years! I'd written ten books before Alex Rider. Certainly, Alex Rider was a breakthrough book, I knew it at the time, I knew it from the time I wrote the first sentence that it was going to be different.

Don't forget, the world of children's books is also changing at that time. Because of the success of Harry Potter, publishers were suddenly aware that there was money to be made out of kids books: you didn't need to sell 3000 books and give away a teddy bear to think you'd succeeded, you could raise your ambitions. So it was part of a new wave that I was riding. The book was the right book at the right time, and I knew it was going to do well.

Stormbreaker sold 25,000 copies as I recall in its first year. My books normally sold about 10,000 copies. Point Blanc then went on to sell 50000, the one after 100,000 and eventually sometime along the line, I was suddenly counting in the millions.

How did it feel? It changed my life, of course, but not in ways that are easy to quite define. My life is spent sitting on my own in a room with a computer. And here I am, 20 years after Stormbreaker was published ,on my own in a room with a computer. Perhaps the difference is that the room has a nicer view.

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Obviously, the books are still children's books. There's not much sex but there's quite a lot of violence, sometimes quite graphic -- the jelly fish in Stormbreaker for example. Did you ever get pushback from publishers?

Dare I say it but your childhood memories are slightly misleading you because I think the violence in the Alex Rider books is very carefully contained. I'm happy to say that in the 21 years, I've never had a single complaint about violence in the books. Not one. Not from parents, not teachers, not from countries where they have stricter codes.

Occasionally, my publisher has caught me short on a sentence. 'Are you sure you need this?' But I think the secret to the violence is context. It's all about context. You know, Itchy and Scratchy, the wonderful Simpsons cartoon, which is all about the violence in Tom and Jerry cartoons, which you forgive because of the context. I think it's true of Alex, too -- because the world is slightly far fetched, because the context is so sort of extreme, the violence doesn't feel too strong or too threatening.

That’s true, but as a reader there were plenty of scenes that I can still visualise today...

The example you gave of jelly fish tank. You know, it is all very scary. And I can imagine as a young person, it may have impressed you, but -- actually the jellyfish does end up sitting on a woman's head and she's twitching and throbbing. The violence is a little extreme in that chapter, thinking back. But again, because her name is Nadia Vole, I mean, you cannot really take a character called Nadia Vole that seriously.

Damian Cray, for example, gets minced up at the end of Eagle Strike, he gets sucked into the rotors of a jet. That's a pretty disgusting way to die. But the fact it happens on a tea trolley somehow makes it have a smile. I always think the violence in my books comes with a smile, always, in every single case. It is never gratuitous. It is never sadistic. It is never unpleasant. It always has a smile.

How do you come up with the character names such as Nadia Vole, Damian Cray, Dr Grief?

Well, these days I try to make the characters less extreme in their names. So Mr Grin and Nadia Vole and Eve Stellenbosch, characters who appear in the earlier books, as I have gone on in the series, I realise that they are a little bit young. And actually, if I'm going to take this world seriously, the books do become more serious as they move forward. Therefore, you don't go for quite so comic, extreme character names.

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How do you come up with the plots?

The plots always start in the newspapers. I always find my plots in something in the newspapers that just strike a chord. Nightshade, for example. I'm quite surprised I got away with it.

It's a very dark plot. It's really to do with religious extremism and sort of brainwashing. And it occurred to me that in some religions, these young people being taken away and turned into terrorists was an interesting area for an Alex Rider story. And that's really the story of Nightshade.

Point Blanc was Dolly the sheep, if you look up when Dolly the sheep was cloned, you'll find it's about the time that I wrote Point Blanc.

Skeleton Key was inspired by the Kursk submarine that sank and Putin did not go to the site because he was on holiday. And it nearly lost him power, there was such a kickback. That occurred to me as a good story.

Stormbreaker was based a little bit on Muhammed Al Fayed, the boss of Harrods -- hence the name Herod Sayle.

Do you have a favourite Alex book?

Russian Roulette is one of my favourite Alex Riders, even though Alex isn't in it. It's about Yassen Gregorovich the killer. It was wonderful to write a book about somebody who becomes bad and to examine what it is that makes people evil, which is something that I think about a great deal.

You look at some of the people in politics and in control of the world. Look at the Republican Party? Look at some of the senators -- what were they like as children? What turned them into these characters that they’ve become? So writing about that with a character who becomes a killer was interesting.

Of the actual Alex Rider books in which Alex appears, probably Nightshade is my favourite. I think the plot is really adult and strong and good. I'd love to see a film, which it might be.

For me, it’s Scorpia...

Scorpia was always my favourite for a long time so I’m glad you said that. I think Scorpio is one of the best and solidest of the Alex books and I loved writing it. I love the ending in particular. Completely dead on the pavement. There was such a backlash!

I was writing one Alex Rider book every two years at that stage. And there was such a backlash against Alex seeming to be killed that I had to write the next one in six months to tell all those teachers and librarians who were sending me angry messages that he was OK.

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Is Alex your favourite creation? As well as being your most successful? 

He probably is because he is my most successful. I mean, I would love to see the Power of Five books better known. And again, I dream of the day when Netflix or Amazon or somebody picks them up and makes a series. The Diamond Brothers I'm very, very fond of. I've always had a really soft spot for Nick Diamond. He's Alex Rider with laughs. And I like the fact that the books have jokes and the danger is so absurd all the time.

I like all my characters. It's a bit like the proud parent with the three or four children. 

So you’re not like the writer in your novel Magpie Murders, who hates their most famous creation...

Well, that's more based on both Ian Fleming and Sir Arthur Conan Doyle. I was always fascinated by the fact Conan Doyle creates the greatest detective in British fiction and then hates him so much he kicks off a waterfall.

Fleming used to rail against James Bond: when he wrote the first book, he didn't even want to show it to his publisher. He was embarrassed about it and sort of ashamed of it. And of course, he was sitting on this extraordinary phenomenon. But all through his life he badmouthed Bond.

So I always had a certain fascination with writers who disliked their main characters. But that's definitely not me. I'm very fond of all my characters.

You once told me you had an idea for a final Alex novel, which would involve an adult Alex, emotionally destroyed by MI6, dragging himself out of his bedsit to seek redemption...

My publishers hate the idea! I think I’ve probably gone off doing that as an idea. There's something about Alex's childhood, his youth, his innocence, his goodness that I don't want to mock. I think there is an interesting book in it, but I'm not sure that it would be an enjoyable book. And therefore, no, I probably won't write it.

Alex Rider is currently streaming on Amazon UK