Criminal Minds (2005)

S05E23 Our Darkest Hour

Title: Shadows of the Night Plot: As Los Angeles grapples with a wave of unexpected power outages, a notorious serial killer seizes the chance to reemerge from the shadows. With the city plunged into darkness, he finds the perfect cover to unleash his deadly instincts once more, leading to a chilling escalation of his crime spree amidst the chaos.