Bargain With Death — Hugh Pentecost

J. W. Sassoon, head man of the biggest oil conglomerate in the world, was found dead in his rooms in the plush Hotel Beaumont. Murder, the police said, and Pierre Chambrun, the imperturbable hotel manager, has only hours to find the answers to some lethal questions:
Who as the missing lady who had left the filmy black underwear on the floor next to the victim's bed? Why was the Arab diplomat so terrified that someone would find his top secret documents among Sassoon's effects? What role in the crime did the dead tycoon's mysterious emissary play, a man no one had ever seen? And who was responsible for the disappearance of Sassoon's playboy son, Johnny?
Then the murderer struck a second time, and Chambrun realized that until he could unmask his ruthless adversary, the hotel would be a deathtrap.