"The Sad Night" refers to the terrible battle between the Aztecs and the Spanish when the natives finally fought back against their invaders. Young readers will learn of how the Spanish came to the land of the Aztecs looking for treasure and how Moctezuma II welcomed Hernan Cortes as a god. However, eventually the series of misunderstandings and betrayals led to the one victory of the Aztecs against the Spaniards. In the back of the book Mathews explains more about the Aztecs and Cortes, including an explanation of the day symbols and other signs found on the Aztec Calendar (the giant round one; if you have ever seen it, you will remember it). Although all of the Aztec codex created before 1519 were destroyed by the Spanish conquerors, Mathews creates a dynamic tribute to that style of art and to the Aztec culture that was destroyed.