Peter is away with Professor Kirke, studying for exams. Susan is in America with her parents. Edmund and Lucy are stuck staying with their cousin Eustace, who is very pompous and makes fun of them for their tales of Narnia. Edmund and Lucy are admiring a painting of a ship, which they think is very Narnian. Eustace comes in and thinks they are crazy for liking the painting at all. The painting starts to become real and they are transported into the world of Narnia. They are saved from drowning by the crew of the Dawn Treader. Edmund and Lucy are pleased to see their old friends Caspian and Reepicheep and to find that is has only been three years since they last left. Eustace is appalled by the entire situation and wants to find a way back home.
Caspian is on a quest to find the seven lost Lords of Narnia. They start by stopping at the Lone Islands. They decide to walk across the island and meet up with the Dawn Treader on the other side. However, they are captured by slave traders. Caspian is sold to a man who turns out to be Lord Bern (one of the lost Lords). Together, they come up with a plan to intimidate the governor of the island into freeing the slaves. King Caspian demotes the governor and promotes Lord Bern to Duke of the Lone Islands.
Back on the Dawn Treader, the crew experiences a terrible storm. They realize that they must find land quickly to make repairs. They find an island and Eustace uses the confusion to sneak away to avoid doing any work. It starts raining and he finds himself in a cave full of treasure. However, he takes the wrong treasure when he puts on a bracelet that turns him into a dragon. Eustace realizes how awful he has been and makes amends with the King, the crew, and his cousins by helping them repair the ship. Aslan turns him back into a boy and Edmund finds him and returns him to the group. The bracelet bares the mark of Lord Octesian, one of the lost Lords. They believe that he was either killed by the dragon, or he was the dead dragon they found.
After a quick stop at the uninhabited Burnt Island, they find themselves in a longboat looking at a golden statue in the water. Eustace puts his spear into the water to see how deep it is, but it gets too heavy and he has to drop it. They find that anything that touches the water turns to gold, including the statue that used to be Lord Restimar. After arguing over the island, Aslan helps them realize that it is not worth the risk involved. They name the island Deathwater and move on quickly, making a pack to tell no one about the possible treasures of the water.
Next, they land on the Duffers' island. The group is threatened by an invisible force. They demand that Lucy undo the spell that they cast upon themselves to hid from magician's uglification spell. Lucy makes her way to the spell book in the magicians house. While looking for the proper spell, she is almost tempted to use a spell on herself to make her the most beautiful woman in the world. Aslan appears to her and brings her back to herself. She finds the spell and makes everyone visible again. They find that the Duffers are a sort of monopod dwarfs.
They stop at the Dark Island (aka The Island Where Dreams Come True) and find Lord Rhoop, who begs them to either rescue or kill him. The others agree that it must be a terrible place after he explains that it isn't day dreams that come true, but the dreams of when you sleep.
Their last stop is at the Island of Star. They find the last three lords sleeping at a table covered in a feast. They are weary about eating the food, thinking that they will sleep as well if they do. They meet a fallen star, Ramadu, and his daughter, who encourage them to eat the food provided. Ramadu informs the group that the only way to wake the three lords is to sail to the end of the world and leave one behind.
When they get to the worlds end, Reepicheep is more than happy to be left behind, as he has been sung to about this being his quest. Caspian wants to go as well, but after the crew protests about him needing to be king and a visit from Aslan, he realizes that he must return to his kingdom. Edmund, Lucy, and Eustace go on to find Aslan. The lion informs Edmund and Lucy that they will not return to Narnia, and they will have to learn to know him by another name in their own world.
Back in their own world, everyone is surprised by the change in Eustace. He even makes a comment about how his mother will blame it on Edmund and Lucy's bad influence.
The Chronicles of Narnia:
The Lion, The Witch, and the Wardrobe
The Voyage of the Dawn Treader
The Silver Chair
The Horse and His Boy
The Magician's Nephew
The Last Battle