As artifacts of great power are at the center of The Book of Doors, ethics and morality surrounding this power are natural questions that come up for the characters throughout the narrative. When Cassie first discovers the Book of Doors, she doesn’t yet realize that other books of power exist in the world. However, even this singular object raises numerous ethical issues. A small, less dire example of this happens when Cassie and Drummond dine at a cafe and then leave without paying; Drummond is distraught at their inadvertent theft, yet Cassie laughs it off. With the Book of Doors, it would be very simple to never have to pay for anything again. Izzy, taking a pragmatic approach, also voices her concerns regarding the potential to use the Book of Doors in unscrupulous ways:

‘Imagine a sicko who can get in and out of any woman’s bedroom,’ Izzy said. ‘Anywhere in the world. […] You could go to another country and commit crimes and come back here and nobody would know who you were. Even if people thought it was you, you would have the perfect alibi of being in another country.