Almost an entire year has passed since the events of the War of Two Worlds, and Arthur has returned home to his grandparent's house, home of the Minimoys. The sky is looking clear, the telescope has been repaired, and even his father is allowing him to visit his tooth-sized friends. But on the night of the tenth moon, a mysterious professor arrives at the Suchot household, determined to expose the Minimoys and their magic to the world. Reunited with the cunning Max, the redeemed Darkos, the hilarious Betamache and the beautiful Princess Selenia, Arthur must find the strength to fight against an enemy capable of turning his world upside down forever.

In the next chapter of the Arthur franchise, Arthur will embark on his greatest adventure yet! Ten moons have passed since the Professor invaded the Seven Kingdoms, and Arthur, after a hard school year, is returning to his love, Princess Selenia. With the moon shining brightly, and Maltazard nowhere to be seen, Arthur is excited for the perfect night him and Selenia have been dreaming of since the day they first said goodbye. But an ancient enemy of the Minimoys has awoken, intent on destroying anything and everything Arthur holds dear. And when the Sword of Power is destroyed, Arthur must battle through the Seven Kingdoms on a great journey to repair it. Within this journey, Arthur is reunited with the feisty but caring Selenia, and her hilarious brother Betameche, as well as some new allies in the form of his school friend: the wisecracking Dylan, and Gardenia, the princess of the Third Kingdom. As myths, stories and legends come to life, it's time for Arthur to decide what kind of king he wants to be... The Sequel to CasualPrince8's 'Arthur 4: Defender of the Seven Kingdoms', and the greatest adventure of the Arthur and the Invisibles franchise to date, Arthur will show everyone what we hardcore fans already know...that the smallest heroes can do the greatest things!