Secret of the Water Dragon (Dragon Masters #3) by Tracey West

In this third book in the series, someone is trying to steal the Dragon Stone. Drake soon discovers that the thief is his friend and fellow Dragon Master, Bo! Could the dark wizard somehow be behind this? The Dragon Masters must find a way to protect the Dragon Stone--and keep Bo's family out of danger. Will the secret to solving their problems lie with Bo's dragon, Shu? Drake is about to find out!