Hmmmm ... a couple guesses from a quick, tailored Google search of the Library: perhaps, "Chastity Belt Terror"? Or "Emily's Predicament"?

Google offers a nice trick. If you enter a search string followed by the word "site:" and a site name, the Google searches just that site for you. So "chastity belt" site: www . bdsmlibrary . com (excuse the weird extra spaces, they're necessary to keep the address from resolving to a direct link) would return every use of the phrase "chastity belt" on this site. My search just entered three of the variables you were looking for ("chastity belt," vibrate, plugs), which generated a couple hundred on-site leads. Just glancing, these seem more promising than the rest.

For what help that offers,

Solis