Doña Pura, don Benito and don Augusto are three venerable old people who usually coincide each month in the queues of the mutuality windows to collect their pension, an opportunity they take advantage of to talk about life. When they learn that the old don Felipe, an acquaintance, is very sick and is alone and without money for a decent funeral, they decide to ask for a loan to help him, but, as they do not grant it, they decide to rob the savings bank. To do this, they will plan everything thoroughly and manufacture a homemade explosive.

An Italian submarine commander manages to sink an English warship and take its very British commander as prisoner. The film is based on the relationship which develops between the two characters.