Friday, July 18, 2014

Countdown to August 7th: Sophia Bennett on The Castle

Today the lovely Sophia Bennett is joining us once again about her new book The Castle. Enjoy!

It’s so exciting to see The Castle in its final, printed edition, with the beautiful, mysterious girl on the cover and the title in shining bronze.

So it’s strange to think that for the year or two that I was researching and writing the book, it wasn’t called The Castle at all. (That title was suggested by Keren David, by the way – author of Salvage. Thank you, Keren!) In my head, this story was always called ‘The Power of Peta Jones’, but in the end, Chicken House, my publishers, decided that could be misleading. This book is not paranormal and Peta doesn’t have any kind of superpower. Far from it. Peta’s ‘power’, as she thinks of it, is a little maths joke she shared with her dad.

It may be a little joke, but it’s essential to the plot. Peta’s dad was a soldier who also loved maths and when he was asked to choose her name, he based it on her birthday. Peta was born on 15 October, the 15th day of the 10th month. ‘Peta’, as well as meaning ‘rock’, also stands for ten to the power of fifteen: ie 10 with 15 zeroes after it, or ten thousand million million. So just as you can have a ‘megabyte’ – a million bytes of data – you can have a ‘petabyte’. Which is a lot, lot bigger.

I got the idea for the name from some Finnish friends of mine. The mother of the family is called Tera (as in ‘terabyte’) and yes, her parents were keen mathematicians too. She called her kids Zetta (10 to the power of 21) and Atto (10 to the power of minus 18) and I happen to think they are the coolest names EVER. Both ends of the alphabet, unusual, interesting to say, interesting to explain … I promised myself that one day I would steal Tera’s idea in a book and … reader, I’ve done it.

Peta’s ‘power’, though, is actually much more than just her name. She’s very focused and almost fearless. She becomes an action heroine without meaning to, just by trying to rescue her dad. That’s what the original title meant to me, and the name and the maths and the many meanings of ‘power’ resonate through the book.

Maths is one of the themes, in a minor way. (But don’t worry – you don’t have to do any calculations of your own!) Peta isn’t scared of numbers – she enjoys them, as I did, growing up. I’ve always loved maths and I wish girls were encouraged to study it more at school. It can lead to some fascinating careers.

I also love puzzles and codes. One of my favourite writers is Simon Singh, who’s written a truly great book about maths problems called Fermat’s Last Theorem, which makes mathematicians sound like the last great adventurers, which in some ways they are. He also wrote The Code Book, about the history of codes and cryptography, and I borrowed ideas from that for The Castle too.

One of the most famous ways of creating a code is to base it on words from a text that both the sender and the receiver know, but someone trying to crack the code can’t guess. It’s called a key. In Sherlock on TV recently a Triad crime syndicate used the London A to Z. Sherlock guessed, of course.

In real life, my favourite key is a poem code written for the SOE agent Violette Szabo by the SOE cryptographer Leo Marks. It’s a very short and simple poem she learned by heart, called ‘The Life That I Have’ and I love it so much I had it at my wedding. I wish it could have saved her life, but sadly she was betrayed and despite fighting off German troops for several hours, Violette was captured, tortured and killed in a concentration camp by the Nazis. She was an inspiring young woman, who deserved to live a rich, full life, and I had her in mind a lot when I was writing about Peta, drawing on all her resources to survive.

My favourite moments are when sender and receiver are using a code in front of the people they’re trying to keep secrets from, and the observers don’t know what’s happening. Peta’s power is connected to her strong and deep relationship with her dad, growing up, and I wanted that to be part of the way she cracks the code.

I love the idea of a password being the key to a problem, and the main protagonist having to solve it under pressure to stay alive. If you’ve read Dan Brown’s The Da Vinci Code, you’ll know that’s one of the reasons it’s such a compelling read. There are a series of codes that have to be solved and, as a reader, you’re on the edge of your seat trying to work them out in time, before something terrible happens. In The Castle, Peta gradually discovers that she is the code, and I can’t tell you how much I enjoyed writing that part of the story.

Towards the end, Peta realises she has to break a computer password, using everything she’s learned over the years from her dad. I’ve based it on a technique that people in the security world use to create strong, memorable but tough-to-crack passwords. So if you read the book, I recommend that technique for creating passwords of your own. In this day and age, staying safe and protecting our information on computers is one of the most important things we have to learn to do. It’s not just Peta – you too can have the power!


  1. Fab guest post! Really interesting - thanks, Sophia, and thanks for hosting, Charli and Tori!

  2. This book sounds awesome remind me to get this.

    Amelia @ YA Bookologists (

  3. As someone who is in the process of choosing a name for my third child I find the meaning and the power behind some name immensely fascinating. Thank you for giving us an insight in to the naming of your latest book and it's fascinating protagonist.


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