I am looking for a story involving male and female (who may be married, not certain) undercover agents (may be police, FBI or private investigators) who are infiltrating a party of a group that enslaves women. The couple has managed to get invited to a private party of the group, and the story takes place as they are getting ready for the party. The male partner is placing the female in bondage, and the female keeps reassuring him that it is alright. She trusts him. Only once she is completely bound and gagged does she realize that the male partner is actually going to join the slavers and that she has just become his slave.
I most likely read it on DA, Gromet's Plaza or Utopia Stories.
Any help?