When Pip and Pelle accidentally come across a magical heart, it turns out to have been stolen from the underground land of Molonia. Since its theft, the heart has literally vanished from the land. Everyone who lives there cries all day and misses their heart's desires. Pip & Pelle, along with their best friend Arie the Postman, are determined to return this heart to Molonia! It's an adventurous journey fraught with danger. A deserted city, underground tunnels, raging seas, a mysterious woman, secretive villages, train chases, and unexpected twists... And as if that weren't enough, there are also the villains Pluun and Grim. Will they manage to get the heart to Molonia in time and stay out of the hands of these two villains?