Restaurant owner Lorenz Adlon plans to build a large and modern hotel in the heart of Berlin at the Brandenburg Gate. He has the support of Kaiser Wilhelm II who often booked the hotel, after its opening in 1907, for state guests. Lorenz Adlon's friends and financiers include successful colonial entrepreneur, Gustaf Schadt.
Alma, daughter of Gustaf and Ottilie Schadt, becomes involved with Frederick Loewe, son of the driver. To avoid a scandal, Ottilie Schadt claims the secretly born daughter Sonja as her own child. Gustaf and Ottilie arrange for Alma to marry the noble officer Siegfried Geschirr, but she refuses and turns to the American photographer Undine Adams, with whom she eventually emigrates to the United States where she remains until after the First World War. Her daughter Sonja stays with her grandparents and is raised as their daughter. The child's father, Frederick Loewe, gets a job as a Page in the Hotel Adlon, where he rises to the position of Concierge.
The first part ends with the First World War and the revolution in Berlin, which eventually leads to the end of the Empire. After the loss of German colonies Gustaf Schadt returns to a fading Berlin and dies shortly thereafter. On his deathbed he shares with Sonja that in truth her supposed sister Alma is her mother. Alma returns to Berlin with her partner Undine for her father's funeral. She also contacts Frederick Loewe and is finally brought together with her daughter. Accompanying Alma and Undine is a German American, Hedda Berger, whose appearance in the Adlon arouses the interest of Louis Adlon.
