The time is WWI. A mysterious Italian secret agent known only as "Spy 77" has been responsible for the undermining of Austrian battle plans. Captain von Hombergck (Carl Diehl) makes it his mission in life to reveal the identity of the elusive Spy 77. Along the way, he falls in love with beautiful Italian marchesa Marcella Galdi (Greta Nissen) -- so guess who she really is? Choosing love over duty, Marcella willingly sacrifices her own life to save Von Hombergk's. A little comedy relief -- or even a song or two -- wouldn't have hurt this picture at all.