Fire Opal and the Mysterious Sulx: Book 2

In an ordinary town, on Fletcher Street, which you probably have in your town as well, there is a very special house, where Mr. Froggy, Karenna, Simon, and Lion live. The friends are very excited: the mysterious sulx, a legendary creature, is somewhere close. They find a nest, some feathers and paw prints, which belong to the sulx. Why is she here? And is it true that the sulx is stealing little kids from their parents? Together, with the magical, shape-shifting submarine, known as Fire Opa...