The Dark Atonement. The Cold War Legacy Series

German translator Lena Hoffman thought her grandfather died years ago. But the unexpected arrival of a cryptic postcard seems to indicate otherwise. As Lena delves into her grandfather's past and uncovers information about him and his cancer research work in East Germany four decades ago, she unwittingly puts her own life in danger. Dr. Devlin Mills works as a cancer researcher at the National Institutes of Health and lives across the hall from Lena, although they've never formally met.
But when Lena is nearly run down by a vehicle, Devlin finds himself thrust into the role of protector. As their lives intersect, the pair find themselves in a race to discover the whereabouts of her grandfather-and whoever wants to silence him-before the past catches up with the present.