Like the Harry Potter books, the success of the Hunger Games trilogy is built on word of mouth while its author stays low key, writes ANNA CAREY

WITH HER NEW BOOK, Mockingjay, selling more than 450,000 copies in the US alone in its first week of publication, Suzanne Collins is the best-selling author you've never heard of. Her Hunger Games trilogy, of which Mockingjayis the final volume, has become hugely successful on both sides of the Atlantic since the first title was published, in 2008, and a big-budget film is in the works. Yet Collins has done very few interviews and received little mainstream coverage here. The trilogy is a rare word-of-mouth success.

“I haven’t seen a lot about her in the media at all, but I’ve definitely noticed the sales building up,” says Niamh Colgan, a children’s bookseller at Waterstone’s. “It was slow in the beginning. It was when the second book came out that it started to move. The first wasn’t really doing that well, but when the second came out more people started looking for it, and then we had a lot of people waiting for the third.”

This steady increase in sales as a series progresses is the mark of the word-of-mouth hit – neither the Harry Potter nor the Twilight series was an instant smash. It wasn’t until the third Potter book, for example, that sales started to soar and the media took notice.

The Hunger Games trilogy is set in the nearish future. Civilisation has collapsed, in the US at least, which is now known as Panem and divided into 12 districts, all ruled by a central state called the Capitol. Every year each district offers up two children, who then fight to the death in a vast and complex arena while the nation watches on television. When 16-year-old Katniss Everdeen’s little sister Prim is chosen, Katniss volunteers to take her place.

Collins was strongly influenced by the Greek myth of Theseus and the Minotaur. “In punishment for past deeds Athens periodically had to send seven youths and seven maidens to Crete, where they were thrown in the labyrinth and devoured by the monstrous Minotaur,” she said recently. “Even as a kid I could appreciate how ruthless this was. Crete was sending a very clear message: ‘Mess with us and we’ll do something worse than kill you. We’ll kill your children.’ And the thing is, it was allowed; the parents sat by powerless to stop it. Theseus, who was the son of the king, volunteered to go. I guess, in her own way, Katniss is a futuristic Theseus.”

Collins has also spoken of being inspired by reality television. “I was channel surfing between reality TV programming and actual war coverage when Katniss’s story came to me. One night I’m sitting there flipping around, and on one channel there’s a group of young people competing for, I don’t know, money maybe? And on the next there’s a group of young people fighting an actual war. And I was tired, and the lines began to blur in this very unsettling way, and I thought of this story.”

But reality shows and ancient myth aren't the only familiar elements of the books. There are traces of everything from Death Race 2000to The Running Man, although the most obvious possible influence is Battle Royale. Made into a successful film in 2000, the Japanese writer Koushun Takami's 1999 novel is also set in a dystopian future in which the government controls the populace by forcing randomly selected groups of schoolchildren to fight to the death.

But while Battle Royaleis a cult classic, it never became a mainstream international hit. So what is it about Hunger Games that has caught the imagination? It's partly down to their charismatic, flawed heroine. Katniss is brave and tough, headstrong yet self-aware. The relationships between the characters are pleasingly complex. Collins isn't a particularly elegant writer, but she's a fantastic storyteller. There's a lot to enjoy. As the author said recently: "Some are attracted to the dystopian world, others are there for action and adventure, still others for the romance. The readers are defining the book in very personal and exciting ways."

And they're telling their friends. "Before Twilightwas really big I had girls coming in after school saying that a friend told them about this book, and they thought it was called Twilightbut they weren't sure," says Niamh Colgan. "The Hunger Games aren't quite as big as that now, but people do come in and ask for it without being sure about the name – they'll tell you about the plot."

It’s impossible to predict what books will take off in this way. Philip Reeve’s complex and moving Mortal Engines books are also set in a dystopian future, which is much more vividly and convincingly realised than that of the Hunger Games. But despite attracting critical raves and devoted fans, they have never achieved the same sales. LJ Smith’s Vampire Diaries books, first published in the early 1990s, are vastly superior to the Twilight saga, which deals with similar themes. Yet although they have belatedly been made into a successful TV show in the wake of Stephenie Meyer’s hit, girls weren’t queuing up for them back in the 1990s.

So maybe it's just a question of having the right idea at the right time. Just as Meyer's creepily chaste characters may have appealed to girls who saw them as an escape from an oversexed world, post-apocalyptic fiction makes us realise that, even though we may be experiencing a recession, things could be worse. " The Roadwas huge last year," says Colgan. "Books with that end-of-the-world feeling make you think what's the most important thing in life. And it's never money: it's always relationships, families and friends."