"The Voyage of the Dawn Treader" follows Edmund, Lucy, and their cousin Eustace as they embark on a nautical adventure with King Caspian aboard the ship Dawn Treader. Their quest is to find the seven lost lords of Narnia. Along the way, they encounter magical islands, mythical creatures, and face inner struggles. Eustace undergoes a transformative experience when he is turned into a dragon and learns humility and compassion. Ultimately, they confront darkness in the form of a malevolent green mist, and through bravery, teamwork, and faith in Aslan, they overcome challenges, fulfill their quest, and bring peace to Narnia once again.