Cale finds an urgent message from Curiel, the medicine man who is in the dungeon accused of chopping the talking trees. In order for Cale to talk to him, he must sneak into the dungeons of Mayor Wickenburg’s castle. But as he’s approaching the castle, he gets caught by the mayor and his son and sent to the dungeon himself. Once there, he sees Curiel chained to the ground and very sick. Curiel gives Cale a mysterious map. Cale uses his pigeon to send the map to his friends while he escapes from the dungeon through a secret passage. The passage leads him to the Green Caves, a strange place full of stalactites and stalagmites and a mysterious tree in the middle. In the mean time, Cale’s friends get the map and head to the caves where they meet their friend. They search the cave and after talking to Ridel, discover that in the cave there are hundreds of talking books begging them for help! The four friends decide to take the books to safety, but as they are loading them into Mondrago’s wagon, they hear steps and a big roar! An evil dragon and his master are approaching! They must leave the caves right away! But first they need to recover the seed from the breadfruit tree!