Letter 54 is a letter written by Luna Aureum in the Hopeless Fountain Kingdom universe. It was revealed on May 18, 2017, when American electropop artist Halsey guided her fans to the official HFK website. It can be seen by clicking on the "l" in the floating "hopeless fountain kingdom" text and scrolling to the bottom of the page. The significance of the letter and whether or not there will be more are both currently unknown.
- Please note: the letter contains several random letters, symbols, and numbers. It is possibly part of a code.