Les Ruines paints a picture of life in southwest France during the dark years of the German occupation towards the end of the Second World War. Almost seventy years later, a young woman stumbles on a mystery from that period and embarks on a mission to seek the truth.

Her quest takes her on a journey of revelation about the chaotic weeks that led to the fragmented liberation of France. With her marriage falling apart, she invites a close friend to accompany her, leaving her husband at home. The two women encounter a strange atmosphere of reticence amongst local inhabitants as they uncover evidence of grim secrets buried in the ruins of a former fortress and chateau.

Her obsessive investigation brings her into contact with Marcel, a former member of the maquis. His reticence to discuss his own involvement leads her to delve deeper into the past. As she learns about the terrifying exploits of the Das Reich 2nd Panzer Division during its march from Montauban to Normandy, dark secrets begin to emerge.

On her return to England, her personal life continues to unravel causing her domestic situation to reach crisis point. As the mystery in France appears about to be resolved, tragedy strikes.