Looking for a Spike fic...

[silverusagi]

Slaymesoftly mentioned this fic on a forum, and I wondered if anyone knew where to find it: "There's an excellent time travel fic in which Spike and Buffy are both send back to 1970's NYC (to fetch a book or something? I forget) She feels obligated to prevent evil Spike from killing Nickie -even though she knows that she could be changing everything, including their relationship." Thanks for any help!