Die Muse des Mörders (2018)

Adult son Oliver lives with has been-crime author Madeleine Montana, who still imagines being a bestseller celebrity and cynically bitches to everyone, even him. A serial killer terrorizes their home town Vienna by actually performing some of the most gruesome murders from Madeleine's books, which she tells the police, enjoying renewed attention. Commissioner in charge Bäumer and assisting inspector Flo duly fear new strikes. The key is in her and Oliver's past.