The Twilight Time (Anna Cameron #1) by Karen Campbell

Anna Cameron is a new Sergeant in the Flexi Unit. On her first day in the new job she discovers she'll be working with her ex, Jamie, now married and with a child. In at the deep end emotionally after many years without him, she's also plunged headlong into the underworld of Glasgow's notorious Drag—the haunt of working girls, drug dealers, and sad, seedy men. Someone is carving up the faces of local prostitutes, an old man has been brutally killed, and racist violence is on the rise; Anna must deal with all this alongside tensions and backstabbing within her own team. Atmospheric, affecting, and beautifully-written, The Twilight Time is a stunning debut from a remarkably talented new crime writer.