Cayetana, her boyfriend Paco and Venancio, her foster brother, commit small thefts and, from time to time, spend a few days in jail. Until they meet with Federico, a thief who has traveled abroad and convince them that using European methods success is guaranteed. Paco then decides to act scientifically and seizes a hospital surgical equipment. When they want to realize, poor Venancio is forced to give an injection to a dentistry patient and, even worse, Paco has to pull out a tooth. And all that, before entering the operating room
 Tony Leblanc
Paco 'Cocosabio'
 Concha Velasco
Cayetana 'La Gandula' (as Conchita Velasco)
 Alfredo Landa
Venancio Torralba 'El Torralba'
 José «Saza» Sazatornil
Don Tadeo Ramírez
 José Bódalo
Don Ernesto Dávila, inspector de policía
 Manolo Gómez Bur
Don Federico Martínez Hojas 'El Tizona'
 Margot Cottens
Juliana, esposa de Don Tadeo
 Tomás Blanco
Don Aurelio