Vasco is a medical student in Lisbon, supported by his rich aunts, whom he had falsely told he had already graduated. In fact, he devotes himself to a bohemian life, preferring the popular fairs and pretty women, especially Alice, a seamstress from the Castelinhos quarter, which rather upsets her ambitious father, tailor Caetano, who is familiar with Vasco's debts. After failing yet another final exam, he is surprised by his aunts' announcement that they will visit him in Lisbon to see his practice.

Vasco Leitão, vive da mesada das tias, que vivem em Trás-os-Montes, que nunca vieram à capital, e o consideram um aluno cumpridor. Ora, o Vasco prefere os retiros e os arraiais, as cantigas populares e as mulheres bonitas, em particular Alice, uma costureira do Bairro dos Castelinhos, o que não agrada ao pai, o alfaiate Caetano, sabendo-o crivado de dívidas... Os azares de Vasco sucedem-se: no mesmo dia em que é reprovado no exame final de curso, recebe uma carta em que as tias lhe anunciam uma visita a Lisboa!...