Dear Wormwood acts as a volume II to Through the Deep, Dark Valley. While Through the Deep, Dark Valley is about the protagonist's past, Dear Wormwood is about the character's future.

The duo explains, "This album is a collection of letters, all written by a single protagonist and addressed to a single recipient, a conversation to which the listener is an observer as a relationship gone wrong reaches its breaking point - the words and music are at times affectionate and bittersweet, at others resigned and resolute."