Take the first and last letters of each footnote in Chapter 1 to get: AR GO SY EV ER Y19th 1900H RS Which turns out to be a message from Filomela to Straka that she would go to Argosy Hall on East 38th Street at 7 pm.
The second footnote in the chapter reveals a Playfair Cipher. Using the chapter title “Gemini” and matching the paired letters of the fake names mentioned (OH HU BW HA MG SY) reveals“Looper Agent” as the message. Jen hypothesizes that Filomela was warning Straka about Looper, though Eric thinks that Looper and Straka were the same person.
Footnote 5 contains the message “APRIS BOUCHARD IS HW.” Take the two letters on either side of each S with a dot just below it to reveal the code. Eric suggests the code is talking about ARP Syndikat, a Dutch weapons manufacturer. Jen further connects Bouchard and the weapons manufacturer to Horst Wechsler.
The first footnote of the chapter titled “Agent X” lead to a code surrounding the words beginning with “ex” in each of the footnotes. Directly after each of the “ex” words reveals “AVOID GRAND CENTRAL KEY STOLEN ASSUME BAG GONE I FAILED.” The meaning behind the message is still unclear and up for some interpretation.
The chapter entitled A Sleeping Dog contains footnotes with very specific years. These years follow the Nihilist Cipher, which is a message revealed using numbers. Using keywords “sleeping” and “dog” and the last two digits of each year mentioned throughout the footnotes (66, 64, 47, 83, 64, 33, 46, 86, 53, 54, 52, 43, 72, 85, 66, 46, 64, 44, 72) reveals the message “MAC WAS JUDAS NOT TIAGO.” Eric remarks that this message means MacInnes gave Durand to the fascists, thus giving her over to the enemy and causing her death, not Garcia Ferrara as most people previously believed.
Footnote 5 of this chapter gives a group of letters. The letters provided and the obituary between the pages 262 and 263 connect to each other using a running key. The two texts are connected with the word “impenetrable” to reveal “SUM LOSING HOPE. PLEASE GET IN TOUCH.” Jen and Eric guess that Filomela is talking about Summersby, meaning that Straka was not Summersby.
This chapter uses a rail fence cipher that is “dizzyingly high” with 19 rails using words marked by a slightly elevated letter. The message revealed is “HAVE YOU EVER STOPPED THINKING ABOUT HER HAVE YOU EVER GIVEN ANYONE ELSE A CHANCE.” Jen remarks that that Filomela thought Straka was thinking about Durand and thus wouldn't give Filomela the chance to show she loved him.
The code in the final chapter is revealed using the decoder wheel, which reveals a message from Filomela that states she has always loved Straka and always will.