Chapters 11, 12, 13, 14 Summary

Sophie tells Captain Fache that the numerical code in Sauniere's message is a mathematical prank. Fache is not happy with her solution to the puzzle. She tells him that the series of numbers represents a famous mathematical progression called the Fibonacci sequence. She also tells him that the series of numbers means nothing more than that. Fache makes his disbelief and displeasure apparent, and Sophie leaves. Langdon had just ended his phone call after listening to Sophie's warning message over and over. He excuses himself from Fache's presence and heads toward the bathroom. Fache decides to return to Sauniere's office. Fache has Langdon bugged so he can track his every move from Sauniere's office.

Langdon enters an empty men's room and splashes water on his face. When he looks up, Sophie is there with him. She tells him that he is Fache's prime...