Darcy and Elizabeth: Timeless — Denise O'Hara

AFF- Elizabeth eagerly awaits her sister Jane's letter while visiting Derbyshire with her aunt and uncle Gardiner. But circumstances cause the letter to be delayed by two additional days. The extra time with Darcy changes the course of both of their lives, in ways no one could have predicted... or even thought possible. In a plot twist, you won't see coming, Darcy and Elizabeth find out if their love is truly timeless. FYI- This book has a sci-fi element which brings the couple into the present using cryogenics.