The troubled story of the Churruca family, a noble lineage of brave seamen, descendants of Cosme Damián Churruca, the Spanish hero of the Battle of Trafalgar; from the Spanish-American War (1898) to the end of the Spanish Civil War (1936-39). (In 1950, a new cut of the film was released with less ideological depth and ten minutes shorter.)
A marginal group celebrates Christmas Eve singing and dancing in the street while a millionaire celebrates the feast offering a great dinner to his friends. The millionaire receives a telegram from his sister in America who announces her visit after more than twenty years without seeing each other…
The strange disappearance of the dogs of his neighbors leads Juan to investigate the case on his own. It ends up finding out that the author of the robberies is a young woman called Eloísa, the cocky daughter of a scientist who uses dogs to create an antidote against sleep. Juan and Eloísa fall in love, but he will ask her to leave her luxurious mansion to live only with his salary.
