" De leeuw in de muis" is a beautiful picture book about a mouse that wants to be as brave as a lion. Will he succeed? Trained by the lion A little mouse feels unseen and misunderstood because of its size and looks (literally) up to the lion, who is heard by everyone with his loud roar. Despite his fear, the mouse decides to be apprenticed to the lion. But once he is nose-to-nose with the most powerful predator on earth, it turns out that there is also a scared mouse hidden in that tough lion.