This sex romp is in fact not mentioned until Chapter VI of the book, which begins with the law Professor Lamberti rather innappropriately describing the wife of the former electrician as 'piquante' at a co-owners' meeting in a luxury block of flats on the outskirts of Rome. Lucrezia and Antonio are one of four couples who have applied to live in and attend to the daily activities in the block, and, heavily supported by the Professor who is of course smitten by Lucrezia, the couple are unanimously voted in.
And so Lucrezia begins to dominate the appartment block, in spite of her inappropriate behaviour, such as delivering the co-owners their mail and telling them the contents of the postcards' contents before they've looked at them. But she doesn't get criticised for this, and even when she thinks she's overstepped the mark by opening a telegramme for Mme Soardo she comes up trumps, and even receives a gift of a seventeenth century writing desk from Mme Soardo for her troubles.
Antonio and Lucrezia are discounted from a theft from one of the rooms by the Professor, who tells the police to investigate someone else, although Antonio has been frequenting a bar where some very rough criminal types go. But Antonio is killed shortly after when he speeds round a hairpin bend into a fire engine: the ever-smitten law Professor manages to find the pompiers guilty instead of Antonio, and Lucrezia receives a huge indemnity. She can't go wrong.
Lucrezia goes on to not only pocket her own and her husband's salaries for looking after the building, but she also easily wins over the Professor by telling him that she can run the flats better than the present manager, so she also snags that job (with a 10% increase) on top of what she's already earning.
Added to this, she has two children by Antonio – Alberto (who is to become Count Alberto and maybe a famous tennis player) and Isabella (due to marry Eric, the nephew of the king of Sweden). The reader might be tempted to call Lucrezia a scheming little bitch, which may be true, but she's also highly intelligent and extremely lucky. And Félicien Marceau does humorous novels very well.