Livia, cellist, and Tina, policeman, are two sisters who live with their boyfriends Fabio, osteopath, and Gianni, also a traffic policeman. Under the advice of their gynecologist Nicola, Livia, perfectly able to have children but absolutely against motherhood (so much to insist on the closure of the tubes), decides to act as a surrogate mother on behalf of Tina, who instead fails to have. So for all the time of gestation, the first will have to hide the belly while the second will have to simulate the pregnancy. Both women therefore find themselves living a series of absurd situations that will also involve the other members of the family.