Simon Thorn and the Viper's Pit

The excitement continues for the secret race of animal shape-shifters with a hero “worthy of a young Harry Potter” (Booklist Online).
Simon Thorn's life is almost unrecognizable from a few months ago. Along with a surprise twin brother and an uncle he never knew, Simon has also found his first real friends to hang out, train, and study with at the secret Animalgam Academy. The only piece missing is his mother, held captive by his evil grandfather, Orion, who's bent on taking over the five kingdoms.
To rescue his mother, Simon sets off cross-country with his friends to the reptile kingdom, battling rogue Animalgams and their own doubts and torn loyalties along the way. But if he’s going to stop Orion, Simon will need to keep him from gathering together the fragments of a terrible weapon, or the lives of everyone Simon loves will be at risk.
With action and adventure, this story is perfect for fans of Rick Riordan and Brandon Mull.