It’s fun to be evil. So is the appeal of “You,” the Lifetime one-season wonder turned Netflix phenomenon. Based on the book by Caroline Kepnes, the thriller took great pleasure in showing the sociopathic brilliance of Joe Goldberg, a serial killer with a penchant for obsessing over certain women to the point of violence. For four seasons, Penn Badgley’s repellently charming villain has manipulated his world and the audience around him into rooting for his madness. It’s undeniably a blast to watch someone be very good at their job, even if that job is being a murderer. But in the show’s final season, Joe has, once again, turned over a new leaf. It’s for real this time, honestly!

Joe is back in New York City, living a life of glamor and privilege alongside Kate (Charlotte Ritchie), his CEO wife with her own dark past. He...