story identification - SF book from the 80's or 90's about a Space Cop who is made into a slave with a pain/pleasure implant?

When I was rather young I had picked up a bunch of SF books at the library, one had a kind of interested plot about an undercover Space Cop of some sort who had somehow been turned into a slave.

It might have been part of a series. The main character was female and she had some sort of pain / pleasure implant. She had been turned into the slave of some sort of Space Pirate whom she was intent on bringing to justice or something.

It was rather a graphic book, both sexually and when it came to violence. It also wasn't what you would call well written. Though at the time the idea of a future with some sort of Space Patrol going undercover to capture Space Pirates had fascinated me.

Recently someone mentioned the same book and neither of us could remember its name.

We were both pretty sure it was written in the 80's or 90's and most of it took place on a space ship where the girl was kept hostage. We think that the Pirates hadn't known she was an undercover Space Cop and she may have been drugged and implanted with this device. She might have been a crew member at first (maybe an engineer) that the Captain turned into a slave, we're really not sure about that. We can't even remember how it ends for sure...

Can anyone help us?

Answer

Is it Stephen R. Donaldson's Gap Series?

It starts off with an ugly and evil space pirate walking into a bar with a beautiful woman and gets complicated, dark and (in one scene) nauseating. I think it ends with a galaxy-spanning threat involving several alien species.

The woman, Morn Hyland, suffers from gap-sickness - a mental aberration caused by interstellar travel. In her case, it turns her homicidal and self-destructive, with very tragic results. In an effort to deal with this, the pirate Angus Thermopyle implants her with a remotely controlled brain implant.

I remember it as being a typical Donaldson novel. That is, a book set in a vast and interesting world but spoiled by having completely unlikable protagonists.

Wikipedia entry for the first book.

By the way, I'm not kidding about the "nauseating" bit. This book is one of only two I've read that caused me to put down the book and think about running to the nearest toilet. Those of you who've read it probably know the scene I mean. For those of you who haven't read it - be warned.