Dr. Otto Wilder (musical comedian Peter Alexander) is in town for an important meeting when his eye catches the attractive millionaire Carlotta Ramirez (Maria Sebaldt). While in town Otto visits his kid brother, Ralf, who is best friends with Charley. Ralf and Charley (Peter Vogel) are planning a party in order to meet Ulla and Britta. Unfortunately for the boys, Charley's unknown aunt wants to visit with him on the same night. When everyone cancels including Charley's aunt, the girls want to leave. In order to salvage the evening, Otto shows up at the party dressed as Charley's aunt. Things become increasingly complicated when Charley's real aunt shows up only to see someone dressed in her designer dress! The next day Carlotta shows herself in the dress that Otto had worn previously.