Summary: At Gare Saint-Lazare, Sophie and Langdon buy two train tickets—but then climb into a waiting taxicab, where Sophie tears the tickets up. Langdon continues to examine Saunière’s key, and detects that it has recently been wet. Looking at it under Sophie’s black light, he finds yet another message from Saunière: an address, 24 Rue Haxo. Sophie tells their driver the address, and they are off to this new destination.
Analysis: As if concerned that Sophie might even briefly outshine Langdon as a problem-solver extraordinaire, Brown in this chapter includes another layer of Saunière’s puzzle for Langdon to figure out before she does!