Welcome: Oriental Harry Potter

A couple of years ago, reading children's books on your own in public was seen as a slightly peculiar activity. But now it is almost impossible to get on a commuter train without seeing soberly dressed adults devouring books by Philip Pullman, J.K. Rowling and Eoin Colfer. Now an unlikely new children's book is tipped to capture the imaginations of adult readers in 21 countries, with Hollywood squabbling over the seven-figure film rights. And what is this publishing sensation about? Unlikely as it sounds, this hot ticket is a mystical thriller set in 13th-century Japan. Think of a literary version of Crouching Tiger, Hidden Dragon: exotic locations, fighting skills honed by years of dedication, the intensity of unconsummated love and constant threat from feudal warlords.

There is a black-hearted tyrant, impregnable in his mountain fortress, protected by his famous nightingale floor. Running like a terrace around his sleeping quarters, it is cunningly built so that even the lightest footfall makes it squeak and sing, giving away the presence of an assassin. Meanwhile, hidden in the mountains, a boy called Takeo is unaware of his powers. Adopted by a great lord, he develops ultra-sensitive hearing, invisibility and the ability to appear in two places at once. Far away, the exquisite Kaede, daughter of a great clansman, is trapped as a hostage, treated no better than a servant and fending off the attentions of the guards.

I won't give too much away except to say that Takeo, by then a passionate and disciplined teenager, has the job of taking her into the heart of enemy territory for an arranged marriage.

Even if you suspect that a book set in medieval Japan, which can't decide if it is for adults or children, is not your cup of tea, don't be put off. I picked it up reluctantly, read a few pages and was hooked.

After the thrilling climax in the dark lord's castle, I finished the book at 3am. The plot is gripping and the writing is beautiful, packed with authentic, atmospheric detail. With several violent but not gratuitously gory scenes, I'd recommend this for over-12s and adults.