Juan is a veteran workshop teacher with no academic training, but a lifetime of practice working on aircraft engines with engineers, who is sent by his company from Madrid to train at the Labor University of Córdoba. There the master of trades will take charge of a young student. Disillusioned by how bad the first tests have gone, he thinks about giving up. But Juan advises him not to do it and helps him in everything he can. Both become friends, but one day the young man finds the real reason for Juan's interest.