Before you search for a raw PDF file, it is important to understand what this book actually is. The Lesser Devil is a novella written by Christopher Ruocchio. It is not a standalone title; rather, it is Book 1.5 in the Sun Eater series (falling chronologically between Empire of Silence and Howling Dark ).

Searching for "The Lesser Devil PDF free download" will likely lead you to pirate sites (such as Z-Library, LibGen, or various Reddit file-sharing threads).