Greg may live in a tree house outside his parents' home in Melbourne, but he thinks he is just a normal boy. Until, that is, the day he has to go on a mission to find his uncle Bart, the 'black sheep' of the family. This takes him down a strange river to a threatening and even stranger land of swamps, Jumping Belts and tree-top cities, in which he must use his special powers to defeat the tyrannical new mayor... Weird creatures abound in this new tale from Mark Hazell.