An elderly woman believes that a precious treasure holds the key to finding her missing brother, who was kidnapped by the Nazis during the Second World War, and Jean seeks Dom's help to reunite the siblings. Meanwhile, Madame Blanc continues to watch Jean from a distance.

Judith and Jeremy throw a 1980s themed 35th wedding anniversary party. Jeremy's brother and sister-in-law, Harry and Cressida, and Judith's sister, Mary attend the party.

Albert Gilbert is left unconscious by robbers when a rare painting is stolen from his home and Caron calls upon Jean for her expertise in the investigation of the theft. Meanwhile, at Charlie and Simone's pawn shop, a local man demands his money back on a fake painting.

Caron enlists Jean and Dom's help when a valuable relic from the local church is stolen, and priest Father Donadieu is discovered murdered. Meanwhile, the Connors have an eventful week when Niall's mother Niamh pays a visit and it quickly becomes apparent that she and Celine are not on amicable terms.

Dom’s wife Georgina returns with outwardly heartfelt declarations of love for him, but he becomes suspicious of her motives. Jean begins preparations to leave Sainte Victoire, but her plans are interrupted by a late-night intruder in her cottage.