On a hunting expedition,the King of Ireland is distracted by a swan who is casting away one of her young. Perplexed, the King seeks council with his druid who explains that in nature any living creature will send its thirteenth offspring into the world to fend for itself. The King himself is no exception to these natural laws and so with a broken heart he casts out his eldest son who then rides off into the Eastern World disguised as a cow herder. Soon the prince has to battle with fierce giants, great warriors and a giant sea serpent to stand any chance of winning the Eastern Princesses hand in marriage.