If you weren't looking for the Michelle Gagnon novel, you might be referring to:
The narrative follows , a recovering con-artist and college student in Tennessee who narrowly escapes becoming the sixth victim of the "Pikachu killer"—a serial killer obsessed with Pokémon. KILLING ME
: Amber is about to be murdered in a decrepit basement when a mysterious masked woman breaks in, kills the psychopath, and frees her before disappearing. If you weren't looking for the Michelle Gagnon