Spain, late 19th century. Judge Javier Zarco finds in a cemetery a skull pierced by a nail and suspects that a murder has been committed.

A woman who has walked out of an unhappy marriage is unsuccessful trying to earn herself a new living and gets mixed with a man who is a murderer and tries to incriminate her.

The old hidalgo Don Alonso Quijano, maddened by the excessive reading of books on chivalry and determined to become a famous and heroic knight-errant, leaves his village and sets out on the road in search of adventure, accompanied by his faithful friend Sancho Panza.