Greenwild

Daisy Thistledown's magical adventure continues in The City Beyond the Sea, the spellbinding sequel to Blackwell's Children's Book of the Year, Greenwild: The World Behind the Door by Pari Thomson.
Across the ocean, a magical adventure awaits . . .
Daisy Thistledown and the Five O'Clock Club might have defeated a terrifying enemy, but their journey to find the missing Botanists is just beginning. Their only hope: to find the legendary Iffenwild, a mysterious city hidden beyond the sea and lost to time.
But a strange, wild magic is stirring beneath the waves. It will take all of Daisy's courage and determination – and the trust of a new friend – if she is to discover the truth that haunts Iffenwild, and save the magical world before it's too late.
'An eco-thriller every child should read' - The Telegraph on Greenwild: The World Behind the Door