Simon Thorn and the Shark's Cave by Aimee Carter

Bloomsbury, 2018. ISBN 9781408858059
(Age: 9-14) Recommended. Simon Thorn is an Animalgam which is a secret race who can each shift into animal form. There are 5 Animalgam kingdoms, birds, insects, reptiles, mammals and the underwater world.
Simon has a secret, he can shift into animals from any kingdom. He has to keep this rare gift a secret, for the leaders of the five kingdoms would destroy him. This is the third book in the series but the first I have read, so it was a little confusing at times. The author does her best to succinctly fill in past information from previous novels but I recommend that the books are read in order to gain a better understanding of the plot.
Each book is dedicated to a different world and this novel is set underwater as the title suggests. Simon, his twin brother and other shape shifters are grudgingly allowed to visit the underwater kingdom.
Simon's evil grandfather, Orion is planning on taking over all the kingdoms and needs the scattered pieces of a terrible weapon to achieve his aim. One of the pieces is hidden in the underwater world. Simon needs to find the piece before his grandfather but this is difficult to do in the militant, guarded sea kingdom. Aimee Carter has portrayed the underwater kingdom as being very regimented with the creatures behaving like soldiers in the army and schools of fish are compared to parading military.
These fantasy stories take the reader into different focus worlds, where Simon has to face danger and solve difficult problems. He is a young hero who has to overcome extreme odds, similar to Percy Jackson in his mythical world.
Aimee Carter has written young adult novels before embarking on this 5 five book series. I would recommend these books to students aged from 9 to 14 years.
Jane Moore