Rapture in Death
Eve can't even get away from murder on her honeymoon. Someone is doing something to people to make them commit suicide. Mavis draws the attention of a music mogel who is illegally trying out mind control. He experiments on both Eve and Roarke to have them experience dark sex. Eve wants to pin the murders on him but they just don't fit. Again, the villain is someone who works for Roarke and is a sociopath.