A year after she discovered a tiny dragon on the beach, life is getting back to normal for Mari Jones and Gweeb, when two unexpected events turn it upside down again. First comes the news that Mari's mum Rhian is expecting a baby, meaning that her boyfriend Gareth and Mari's best friend Dylan will be moving in with them on the farm. Even more incredibly, Gweeb's family have returned to lay their eggs in the same cave where Mari first found her secret dragon. With tourists flocking to the beach for the summer, Mari has her work cut out to keep the dragons hidden and safe, especially when disgraced scientist Dr Griff Griffiths turns up on the hunt for a story. And when Griff manages to find and steal Gweeb's precious egg, Mari must stage a daring rescue mission before it's too late.