Madison Kelly, a San Diego private investigator, arrives home to a note stabbed to her front door: "Stop investigating me, or I will hunt you down and kill you." The only problem? Madison hasn't been investigating anyone--she's been taking time off to figure out what to do with her life. But how does she prove a negative? The only way to remove the threat is to do exactly what "Anonymous", the note writer, is telling her not to do: investigate to see who left it. Could this have something to do with the true crime podcast she's been tweeting about, and the missing girls?