Who does Lucy meet in Narnis What is the problem?

In "The Lion, the Witch and the Wardrobe," Lucy meets Mr. Tumnus, a faun, in Narnia. The problem arises when she discovers that the White Witch has cast a spell over Narnia, making it always winter and preventing Christmas from coming. Mr. Tumnus reveals that he has been ordered to capture humans and deliver them to the Witch, which puts Lucy in a precarious situation.