Pedro is getting used to the thrilling life of the Adventuremice. But one stormy night, hefinds something he's only ever dreamed of seeing: a real, live mermouse! This littlemermouse is lost, and Pedro and the Adventuremice need to get him safely home.

They must summon all their bravery and brilliance, plunge into the depths of the oceanand find the mysterious Mermouse C ity. It won't be straightforward, but it will be anotherexciting, friend-filled adventure for Pedro and the team!