The brothers Leon and Gereon are sitting in front of the lion enclosure at the zoo and are bored. Suddenly the lion speaks to them, the cage disappears and a new world opens up before them: the evergreen forest. Leon and Gereon transform themselves into the brave knights Iwein and Gawein, who are at home in King Arthur's court. But Iwein's days there grow longer and longer, he decides to go out into the world. With his brash appearance, Iwein challenges the lord of the castle next door, which he finds anything but amusing. At the source of the thunderstorm, a duel ensues between the men, which ends fatally for the lord of the castle. The widowed lady of the castle Laudine is deadly sad. But her heart has a mind of its own and begins to beat for Iwein's heart of all things. Iwein's heart also warms when he thinks of Laudine. But they have not reckoned with Gawein, who is terribly bored without Iwein by his side.He persuades Iwein to seek new adventures with him. Laudine sets her beloved a deadline: he must return to her after one year. The two knights set off and achieve one success after another. In the throes of victory Iwein forgets the time and stands Laudine up.
Lunete, Laudine's lady-in-waiting, curses Iwein for breaking his promise. The curse makes Iwein forget who he is. He now lives without memory with the Wild Man, where Lunete sees him and takes back her curse. Slowly he begins to remember. Now he wants to prove himself again and is immediately given the chance: A lion fights a dragon in the Everwood. Iwein rushes to his aid and kills the dragon. Out of gratitude, the lion becomes his best friend. Together they fight the giant Harpin and the double knight. Laudine's heart becomes impatient and urges Iwein to return to his beloved. At the source of the storm Iwein, Gawein and Laudine meet again. There is great joy at their reunion. Leon and Gereon - no longer the two knights Iwein and Gawein - are once again in front of the lion's cage in the zoo again. The two of them enthusiastically tell their parents and sister about the adventures they had in the evergreen forest.