When a heart murmur obliges Jean-Claude to take exercise, he opts for tango lessons in the studio opposite his office.

There Françoise Rubion recognises in him the older son of her former nanny and chooses him as her dance partner, initially to escape the attentions of an admirer in the same class.

Then the jealous rival reveals that Françoise is to be married and, when she tries to explain things to Jean-Claude at his office, he accuses her of making a fool of him and asks her to leave.

Opening a locked cupboard in his room, he discovers there all the tennis trophies and newspaper cuttings that his parent pretended to have cleared out.

Then his secretary, a spinster with only a dog to care for, confesses to Jean-Claude that she listened to his quarrel with Françoise and advises him not to make the same mistake as she had in the past and to seize his chance of happiness.