Regency London was a bustle of letters and intrigue. Hereinafter, the letters exchanged between characters during the episode of Taboo are grouped together. The letters, generally read by voice-overs of the sender, are listed in order of appearance.
Zilpha Geary's First LetterEdit
- "Dear James,
I am writing this letter in the hope you will read it and see sense. You unexpected return has caused much disruption and anguish. I implore you to relinquish the deed and leave. For your own good as well as others. During your long absence, our father changed. He was not a pleasant man and made many enemies. Your prolonged [...] may turn these enemies [...] Your sister Zilpha." 
Note: This letter, intercepted by Thorne Geary, was not sent. Instead, it was sent an unidentified letter wrote under Thorne's supervision, devoid of pleas.
Robert Thoyt's LetterEdit
A letter was written by Delaney's attorney, soliciting the sale of Nootka Sound. The letter, however, was burned by James Delaney without reading it. The content was known to Brace because Thoyt used to send letters with the same request to Horace Delaney too.
Zilpha Geary's Second LetterEdit
- "Dear James,
The letter I sent to you this morning was written under the supervision of my husband, to whom I am happily married. It is more than ten years since you went away and at the time I was grateful that you had decided to leave England for both of our sake's... Whatever happens with this business of inheritance, and no matter if it results in dispute, I hope I can trust you to keep the secrets of the past buried. Buried in a deeper grave..." 
James Delaney's Blank LetterEdit
An envelope containing a rough diamond addressed to Zilpha Geary, with no further line of explanation.
James Delaney's First LetterEdit
- "Dear Sister,
I am restoring our father's offices I have registered the Delaney trading company with Lloyds of London... And I will ready my ship. So that when the time is right. And the Company has fallen we can leave. I am accruing a band of loyal servants, none of whom have any value to me beyond the facilitation of this greater good. When I left England, I was just a boy. Now I am back, much has changed." 
Zilpha Geary's Third LetterEdit
- "Your leaving England, was the click of a hypnotists fingers. I woke from a trance and realised the depth of our sin. I have found forgiveness in God and in my husband and I want no part in your plans or your future." 
James Delaney's Second LetterEdit
- "But we are the future. Your husband is already past. You can see that by the way that he follows you. You should let him go, poor soul. You torture him. There is enough treachery already surrounding us that there is no need for us to add to it." 
Zilpha Geary's Fourth LetterEdit
- "The arrival of letters at this address does not go unnoticed. My husband is harsh and is a Christian, I welcome it. I deserve it." 
James Delaney's Third LetterEdit
- "Your husband is also a fool. He cannot see all that you are. I have sailed to places where there is no damnation... We used to talk to each other without words in dark corners. Your curiosity and hunger for all that is possible out there. Could never be tethered by based religious morality. Ship insurance. And new China...." 
Zilpha Geary's Fifth LetterEdit
- "Please understand that from this moment I will burn your letters without opening them." 
James Delaney's Fourth LetterEdit
- "Then I will visit you in your dreams. My love." 
Zilpha Geary's Sixth LetterEdit
- "Please, I am your sister. Let all else lie..." 
Countess Musgrove's InvitationEdit
The corpse of one of the henchmen hired by East India Company to interrogate Helga's prostitutes, along with a card bearing the line "Died on Company Business," intended to be a message for Sir Stuart Strange. 
Chichester's Appeals to the British CrownEdit
A series of application to a higher court requested by George Chichester on behalf of Sons of Africa to the British Crown to investigate the deaths of many Africans during the slave trade at the hands of the East India Company; In particular, the wreck of the Cornwallis. 
Zilpha Geary's Suicide LetterEdit
- "Dear James,
at last, I have found a way out of the cage in which I have been living. Eyes I didn't know I had were opened. I saw the limits of my life, the iron bars around my soul. At last, I found a way to slip between them. I intend to leave society, leave London, leave England behind, travel to a place where I will be free. It is a place where, someday, I hope we will meet and be happy. [...] I'm planning to journey to heaven, James. I've realised the truth. My cage is my flesh, I can shed it. The River Thames will take me to God. Death is just the turning of a key in a lock. Whether God will accept me is another matter, perhaps my husband will have spoken of my betrayal. Or perhaps my feelings for you, unforgivable feelings for you, will mean the Thames will take me to a different place. Whatever my destination, if you survive your recklessness, please, keep some part of my soul inside your own." 
- Lorna Bow claimed that Horace Delaney was often writing her long love letters during courtship, along with "beautiful letters" addressed to his own son, describing places he visited in his journeys. However, none of these letters have ever been shown, or read on-screen.
- Most of the letters were written by Zilpha Geary to James in the first season of the miniseries.