Simon Thorn #3: Simon Thorn and the Shark's Cave by Aimee Carter

My name is Jam, and the General, my father, has allowed me to bring my friends back to my home. This has allowed Simon and me to search for the underwater kingdom's piece of the Predator before Orion steals it. The ruler of the bird kingdom wants to unite all the Predator's pieces, so he can use its powers to reign over all Animalgam kingdoms. Unfortunately, the General wanted to move his piece from its hiding place, and we were ambushed by sharks working for Orion. Simon saved us from death by changing into an orca whale, but the General was seriously wounded. We've learned Orion is planning an attack on the compound and has been secretly getting information from a spy inside Atlantis. A war between the Animalgam kingdoms is waiting to erupt, Simon may be charged with treason, and my sister wants to kill his mother. And I may become the next ruler of the underwater kingdom!

You don't need to read the previous books to enjoy this one, but I recommend you do. The format is similar to book two, as Simon and friends try to keep Orion, Simon's grandfather, from getting his hands on the pieces of the Predator. The weapon will allow Orion to change into any animal, which other Animalgams fear. Although he is the main antagonist, his actual character is not directly involved in most of the plot. Simon wants to get all the Predator pieces first to destroy it, so this quest is the main conflict. An added twist to the whole series is that Simon and his twin brother are naturally able to become any animal, although Simon is keeping his ability secret. Even his brother doesn't know, which adds another source of suspense between the characters. The underwater setting of the book limits which characters are able to leave Atlantis and enter the deep ocean waters. For that reason, most of the action in the plot focuses on Jam and Simon. You won't like this book if you don't like humans becoming animals. However, you might learn a little bit about underwater creatures if you give it a shot.