Book Didn't Mention Aliens

Lauren finds herself up a tree dressed only in her undies (not the way she usually dresses to go out). A millennium in the future Elisias newest and youngest perfect finds an anomaly: a fifteenth century monk describes a most improbable holy relic which sounds suspiciously like a bra and pair of pants. Katya, her unusually aggressive guard, an even less appealing alien and sundry other handicaps set out to rescue Lauren. Times a funny thing. It doesnt just pass. Sometimes it turns back and bites you on the bum.