Down with the king

This book is about a species of people Called cryodiles: they look like humans with small tails, blue lizard scales, gills and lungs, lizard eyes and webbed feet. and there is a rebellion against king will the 2nd, the cryodiles are a tribal species and are killed off by king will because they cant pay taxes along with peasants and so the cryodile leader's son and daughter take on a dangerous mission of negotiations and war.

Note: I am not good with Grammer so I am sorry for Grammer mistakes if you see them point them out plz