After hearing about the Church of the Kraken from the members of House Kraken she was out with, Selene wonders if it is similar to the Cult of the Kraken that she heard about while she was at the Pearl Tower.
The premise is that there is a sleeping Great Old One Kraken in the Deeps and, if he rises it will be apocalyptic. Some believe that if the Kraken is kept asleep with a steady stream of sentient sacrifices, the Kraken will be content to slumber and leave the rest of the world alone.
However, there are rumours of even more sinister cults who are attempting to wake the Kraken up in order to destroy the world and remake it in their own image.