From Beatrice Blue, author of the Waterstones Children's Prize-shortlisted Once Upon a Unicorn Horn, comes a beautiful, vibrant story about friendship and protecting our oceans.

Theodore has a little boat and a big passion: collecting fish. He loves nothing more than discovering a new fish for his collection. But one day, he finds something he's never seen before: a tiny creature in a beautiful shell. Ignoring the voice that tells him to leave her alone, he takes her home and puts her in a tank, where she gets weaker and weaker.

Can Theodore learn that the creature belongs in the ocean before it's too late?

Drawn in bright yet soothing, whimsical mermaid colours, this is a bright and beautiful keepsake and a kind reminder to kids to let nature be and look after our oceans. It's a dazzling and sparkling story of magic, friendship and environmental conservation.

This heartwarming story is the follow-up to the critically acclaimed and bestselling Once Upon A Unicorn Horn and Once Upon a Dragon's Fire.