The Wicked and the Naughty (S01E04)

Ellie and Gedeon team up with the cultist Brunner to catch the killer by devising a risky plan that involves bending the law. They stage a fake copycat murder to entice the killer into contacting Brunner. As they navigate this dangerous game, Ellie embarks on a secret relationship with her boss, while Gedeon grapples with the ghosts of his former life as a corrupt narcotics officer, which continues to shadow him.