The Third Day, the Frost

Book 3 of the Tomorrow, When the War Began series. ""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 its winter. They're still here. But so too are Ellie and Homer and their friends.