Gabriel's wife, Irene, decides to investigate the cause of her husband's death. Captured by the French, Gruber, a German spy, is interrogated about the enemy program. Deployed on a mission, the Sentinels discover the work of a German soldier with formidable abilities.

Irène investigates a news item involving Mirreau that appears to be linked to a state secret. At the cabaret "Les Damnés," the Baron discovers that Gisèle has run away. After the tragic loss of a comrade in arms, Gabriel wants to return to Paris to see his son and wife.