What's the biggest danger you can think of? THIS IS BIGGER.

What's the toughest challenge you can imagine? THIS IS TOUGHER.

What's the greatest fear you have? YOU'RE ABOUT TO FIND OUT.

First there was Tomorrow, When the War Began, then came The Dead of Night. Now it's The Third Day, The Frost. And things can only get worse.

'How long do you think they'll keep looking for us?' I asked Lee, as we lay there.

'Until they find us,' he answered grimly. They came in summer. They fell upon the land swiftly and suddenly. Through autumn they spread, like locusts, like mice, like a plague.

Now it's winter. They're still here.

But so too are Ellie and Homer and their friends. Half-a-dozen teenagers with all the odds against them. All they have going for them is their friendship, and their own inner spirit.

How far can courage go? What do you save first when you're fighting for everything - yourself, your friends, your family, your country? In The Third Day, The Frost the answers are as big as the questions. John Marsden is one of the new breed of Australia's writers for young people: lively, fresh, provocative. Many young readers actually turn off the TV and leave their computer games to go and read John's books. And, for a number of them, they are the first books they voluntarily read.