In 1915, French soldier Gabriel Ferraud is gravely wounded on the brutal battlefields of World War I. Officially presumed dead, he is secretly saved and chosen to participate in a highly classified army research program that tests an experimental superhuman serum called Dyxenal.

Gabriel learns he must join the elite Sentinels Brigade if he ever wants to see his family again, who currently believe he is dead. Meanwhile, a violent attack on the program's secret military laboratory sparks a high-stakes investigation that frustrates the commanding Colonel Mirreau.

Refusing to accept official reports, Gabriel’s determined wife, Irène, starts her own investigation into the strange circumstances surrounding her husband’s death. On the military front, French forces capture and interrogate a German spy, desperate for intel on the enemy's own secret program.

The French General Staff issues an immediate order to eliminate the German super-soldier, who now poses the primary threat to the military. While hunting down their specific target, the Sentinels unwittingly march directly into a fierce confrontation with the Übermensch, an enemy of unimaginable strength.

Irène digs deeper into a case involving Colonel Mirreau, uncovering dark state secrets. Meanwhile, at the cabaret Les Damnés, the Baron discovers that Gisèle has fled. Following a brutal defeat on the battlefield, a desperate Gabriel risks everything to slip back into Paris to see his family.