By conducting blood tests, Marthe discovers that Ferraud's body is not eliminating the serum and that Sergeant Djibouti's health is deteriorating. Having become aggressive and uncontrollable during his first mission, Gabriel tries to explain to the doctor how he felt. Meanwhile, Colonel Mirreau questions Grüber about the German army's research into another combat serum. The Baron uses Gisèle's esoteric gifts to locate Grüber and prevent him from talking.