One Good Dog by Susan Wilson

As requested by IcySparx
Adam March is a self-made “Master of the Universe.” He has it all: the beautiful wife, the high-powered job, the glittering circle of friends. But there is a price to be paid for all these trappings, and the pressure is mounting—until the day Adam makes a fatal mistake. His assistant leaves him a message with three words: your sister called. What no one knows is that Adam’s sister has been missing for decades