The premise of the novel, in a nutshell, is basically a somewhat less naval gazing version of Blade Runner. Homicide Detective Zach Forrest works his beat in New Orleans new Red Light District ("Easytown") where prostitution is legalized thanks to the existence of soulless but otherwise indistinguishable from reality sex bots. If you guess a series of murders rocks the district and calls Zach to question, then you'd be right. A city councilman is murdered by his companion and that threatens New Orleans' lucrative sex-tourist trade.
Zach is thus drawn into solving a case he doesn't want to that also includes a romance with the "madam" of the cyber-brothel he's investigating. One rule he can't break, though, is having sex with one of the lifelike machines himself. A police officer who breaks the Immorality Clause of their contract is off the force. [Note: Having lived in New Orleans for a time, the idea of the NOPD not being involved with prostitutes may be the most unbelievable thing in this book of robots and flying cars.]
It's a conservative vision of the future as regular prostitution and drugs are still illegal and there's a huge stigma to using the artificial kind. Sex work is depicted as shameful in the eyes of society even as the women involved (and only women) are decent people. Zach Forrest, himself, loathes Easytown as despite full of legal businesses, it's a dangerous and sleazy sort of place. I actually don't mind this as the best science fiction is about now rather than the future.
Brian Parker does an excellent job realizing the dichotomy of machines potentially having more humanity than the people around them. Zach Forrest is barely functional after years on the force and his best friend is a Siri-analogue that isn't quite artificial intelligence but close enough to be indistinguishable to a schlub like Zach. He has few friends but enough that he can get them involved in his work by accident. He also has the film noir detective quality of being incredibly attractive to women despite being a working class drunk.
The world is well realized and you really can feel this setting with all of its contradictions and ugliness. It's the kind of place where the local crime lord is the most honest and upfront person you're likely to meet. I also liked a surprise with one of the characters which I really should have seen coming but was taken aback by. Then again, you know in a book about a clause to not sleep with robots that our hero is going to at some point.
I'm also a big fan of cyberpunk as a genre and this is the other side of the genre. Whereas so much want to be the next William Gibson or Neil Stephenson, this is far more on the Phillip K. Dick side of things. Make no mistake, it is cyberpunk, though as humanity has not changed because of the technology it has available. It has just found new and interesting ways to exploit it in order to do the same dirty deeds it always did.
Are there flaws to the book? Eh, well things get a little out of hand toward the end as it goes from being about some murders in Easytown to a conspiracy to affect the Catholic position on what sort of sin cyberprostitution is. The only changes to New Orleans also felt like the return of its red light district and the fact Arabs are now a common minority. Even then, I felt like the story was good and worked as a noir science fiction story. In conclusion, The Immorality Clause is an excellent novel and one I heartily recommend.