In this fourth installment of the popular Mermaids Rock series, which features black-and-white illustrations throughout, ocean animals start disappearing from the reef into the mysterious midnight realm—and it’s up to Naya and her friends to find out why!

When ocean animals start disappearing from the reef and end up in the mysterious midnight realm—Naya and her mer-friends decide to find out why. The group sets out to investigate, and when they reach the midnight realm, they find a glowing cave inhabited by a tentacled monster. Then the monster traps Luna, and Naya and her friends need to use all of their creativity to pull off a rescue mission. Features black-and-white illustrations throughout and informational back matter on preserving our oceans. 

Join Marina and her mermaid friends in the beautiful coral reef at Mermaids Rock! Whether they're working together to help sea animals in danger or solving a mystery of the deep, there's always an adventure to be had with the best friends of Mermaids Rock.