Nick Sander tries to cover up the impending bankruptcy of his advertising company from his bride Lilli Brenner. Nick assumes that his money problems will be solved once he marries the banker's daughter. At the same time, Oskar, his 13-year-old son, of whose existence Nick was previously unaware, is on his way from Salzburg to Zurich. When the boy turns up on Nick's doorstep, things get dicey. The groom has no use for an illegitimate child from a dark past. Nick answers Lilli's curious question about who the boy is with a white lie: a Mozart actor for his latest advertising campaign. This slander goes down badly with Oskar, which is why he puts his father under pressure.