Game Theory By Barry Jonsberg. Sydney: Allen and Unwin, 2026.

Jamie is a sixteen-year-old maths whiz. Summerlee, his older sister, is in the grip of a wild phase. Tensions at home run high.

When Summerlee wins a 7.5-million-dollar lottery, she cuts all ties with her family. But money can cause trouble - big trouble. And when Jamie's younger sister Phoebe is kidnapped for a ransom, the family faces a crisis almost too painful to bear.

Jamie thinks he can use game theory - the strategy of predicting an opponent's actions - to get Phoebe back. But can he outfox the kidnapper? Or is he putting his own and his sister's life at risk?

The fascinating thing about this novel is that, like many of Barry Jonsberg's other books, it has an ending you can't quite predict, a little twist that makes you say, "Oh!" It is one I love but can't share because of spoilers. I did suspect who the kidnapper was, then thought, "Well, it can't be, because..." but it was. But that isn't the twist I was thinking of. There is a delicious irony about it. 

Jamie is certain he can work out how to find his sister and her kidnapper through game theory; when his opponent seems to know as much about it as he does, he even rather enjoys the challenge, worried as he is for his beloved little sister. This is his major flaw and makes the book more interesting, even though the reader might, like me, be just a little disappointed that the book isn't actually about that. 

I would have liked a little more detail about the kidnapper before the long, detailed explanation at the end. Although I suspected who it was, the character traits that affected what the villain did were not so evident in the build up. 

Still, it's a good, exciting thriller that should suit boys from about fourteen up.