Life flows peacefully in Yolcos, a beautiful and prosperous port city of ancient Greece, until its people are threatened by the wrath of Poseidon. A young adventurous mouse and the cat who adopted her will then unwittingly aid old Jason and his Argonauts in their quest to save the city. But far more than just a helping hand, the operation will ultimately lead them to confront the most dangerous mythical creatures of mythology and overcome every danger in their stead.