Harem by Appointment, Book 3: Femdom Surprise. Harem by Appointment, #3

Tom has been called to do some plumbing work at a pretty nice house, owned by Ellen, a woman three inches taller than him and who radiates the power of an executive. She couldn't be kinder, though, and is very pleased with his work on her sink. So pleased, in fact, that she invites him downstairs to work on something else. That's when he enters the Palace, Ellen's secret pleasure dungeon, and meets her friend Lucia.
They're both dressed in leather, and they're both going to dominate Tom, much to his enjoyment.