A 'school of communism', located in a small village in the south of France, sends its three most outstanding students to Spain to carry out terrorist activities. However, plans are broken at the border when the three spies confuse their liaison with a priest totally unaware of their activities. The alleged 'agent' sends them to Madrid to his sister's house whose son is a civil guard. The contact with the Spanish life, different from the preconceived vision that they brought from the "school" originates a series of troubled situations that provoke the displeasure of their chiefs.