Commissioner Mendoza must join forces with the honorable civil guard, to stop the activities of a network of drug traffickers with international contacts that intend to act in Spain.

Chino Valdez is a loner horse breeder living in the old west. Partly a loner by choice, and partly because, being a 'half-breed', he finds himself unwelcome almost everywhere he goes. One day, a young runaway named Jimmy shows up at his door looking for work and a roof over his head. Reluctantly, Chino agrees to take him in and teach him the art of raising, breaking and breeding horses, until the pair finally begin to accept each other.

Beliche, a naive postman, suffers from depression because he has almost no letters to deliver. The neighbors to whom Beliche takes their correspondence decide then to launch a plan to receive many more.