Only by Blood is a novel of the search for roots, mother-daughter love, and family reconciliation. A Polish woman receives puzzling news from her mother just before she dies. The novel weaves together the story of Mania a devout, Polish Christian doctor and her mother Krystyna. The two are exceptionally close, as Mania has never known her father. However, in spite of their closeness, Krystyna has always refused to tell Mania about their family or the time they spent together when Mania was small during the war. Their story is mainly told in the present as Mania deals with her mother's aging, her death, and her final words, "Find them ... make it right." She wants to fulfill her mother's last wishes, but has little idea of where to start. Never does she suspect that her search will take her across Poland, back in time and over the ocean. Spanning over sixty years, this story tells about the lengths to which mothers will go in order to save their daughters and the secrets they will keep to protect them from pain. Set in the broader context of the fraught relationship of Poles and Jews during and after the Second World War, it depicts the circumstances that made some ordinary people behave heroically while others betrayed their friends and neighbours.