The clues were in his father's past.
Joaquin Aguirre, a 74 year-old Mexican engineer, dies at the bottom of the sea searching for the wreck of the Spanish galleon Santisima Trinidad, which sank in the Gulf of Mexico in the 17th century, and which he has been trying to find for more than 30 years. When he dies, he leaves his boat El Meridiano to Juan and his eight-year-old daughter Ana. During their journey, the ghost of his father urges him to find the galleon; Juan decides to follow in his father's footsteps and seek the treasure of Trinidad. Finally, father and daughter find a common ground and there is a full identification between them.