Murder at the Hotel Orient by Alessandra Ranalli
This is kind of an offbeat mystery set in a unique hotel designed for "secret liaisons" in Vienna. Sterling is the concierge. One crazy night, 2 people are murdered at the hotel inside their locked room. Since everyone checks in under a fake name, the police need Sterling's help to track down the suspects. Some good twists in the mystery plot and some budding romances. There is a fair amount of sex and violence in this book, if you find that offputting.