Bishop Aringarosa meets with the same officials he originally met in the Vatican. Apparently, he has completed his task a month early. The officials are concerned that Aringarosa wants his payment in bearer bonds drawn on the Vatican bank. Aringarosa knows the bonds are traceable to the Vatican and has demanded his payment in this form as insurance. As he leaves, Aringarosa tells the men he is heading to Paris.

Langdon and Sophie arrive at the Swiss bank, where the recovered key grants them entrance. A guard directs Langdon and Sophie to the deposit box. When they walk away, the guard immediately calls the bank manager to alert him that two fugitives have just come into the bank. Sophie and Langdon learn that they must have an account number to open the box. In the meantime, Fache calls Collet and tells him to get to the bank; they have received a tip from Interpol.

The president of the bank, André Vernet, is called to the bank. Sophie tells Vernet that she has no account number because her grandfather was murdered that evening. Vernet is shocked; he was Saunière's friend. Vernet asks if either of them were involved in Saunière's murder. Sophie assures Vernet of their innocence. Because Saunière was his friend and because Vernet does not want bad press for the bank, he tells Sophie and Langdon he will help them leave the bank undetected. Meanwhile, Langdon believes he has figured out the account number.

Langdon shows Sophie the message her grandfather wrote on the Louvre floor. The first line contains ten digits; the account number is comprised of ten digits. Realizing they get only one chance to enter the account number, Sophie carefully considers the numbers. She decides that the numbers, as written, are too random. She rearranges them into the Fibonacci sequence and enters them successfully. In the crate that arrives, they find a wooden box with a hand-carved, five-petal rose inlay.

Vernet is shocked when he sees they have accessed the account. Sophie tells Vernet that they had the account number after all. Vernet takes them to an armored car and places them in the back. Vernet, who is driving, is stopped by Collet. Vernet poses as a rough truck driver and successfully escapes.

Notes

This section illustrates how Sophie and Langdon need each other in order to be successful on this quest. Langdon realizes that the account number is the number that Saunière wrote on the floor. Sophie realizes that the numbers must be rearranged.