Lucy and Edmund are staying with relatives and are cooped up with their annoying cousin Eustace. Eustace doesn't particularly like his cousins and enjoys making fun of them, especially for all their make believe talk of traveling to another world and being kings and queens of a place called Narnia. Lucy and Edmund dislike Eustace just as much as he dislikes them. While in one of their typical arguments in the spare bedroom, Lucy notices something odd about the painting with the ship. It looks as though the waves are moving and the ship is coming straight out of the painting. Eustace goes to investigate before Lucy and Edmund can warn him about the dangers of magic. All three are soon found to be small enough to climb onto the edge of the painting. They all fall into the painting and find themselves in the sea. They soon find themselves being rescued and brought aboard a boat (the Dawn Treader) by none other than King Caspian. Caspian fills them in on what has occurred while they were away and tells them of the voyage they have just stumbled upon. While his uncle Miraz was ruler, he forced many lords to sail away and never return, as Caspian is now King, he has vowed to voyage and find what has happened to these men.
They set sail on a grand adventure and find many mysterious things along the way. They sail to the lone islands and discover an island where there is a dragon. One with invisible beings and a magician. One where dreams become reality. And past all of these, they journey to the end of the world.