53. The Woman in Room 2805

One June evening in Oslo, a gunshot suddenly rings out from a room in a luxury hotel. Armed police struggle to breach the door, but when they do, they find it double-locked from the inside. On the bed lies a young woman, dead from a single bullet to the head. The death has the initial appearance of a tragic suicide, until investigators look closer. The mysterious woman has no ID, the labels have been cut from all her clothes, and the serial number on her gun has been dissolved by acid. So who was she and, more importantly, who pulled the trigger?