When his wife storms out of a dinner planned in honor of his American boss (because their dog is not allowed to be at the table) an engineer pretends that his secretary is the missus.

The famous American pianist, Hans Martenrood, is playing for the first time in Europe. A young boy is waiting for him in his hotel room after the concert with a letter from his mother, Marie, which explains, that Hans is the father of the boy and that she believes he would be better off being with his father. A short time later, Marie is found in a hotel room, critically wounded by two gunshots. Detective During is put to work on the case. He arrests a suspect, who is identified by the maid and porter as being Marie’s last visitor. At first, the man says nothing; but then he tells the detective Marie’s story.

Princess Stauffenstein has arranged a marriage for her grandnephew Poldi and orders him to meet his unknown bride Steffi. But he falls for alluring dancer Ilonka while his uncle Leopold, sent to reason with him, is enchanted by Steffi.