Ernesto returns to America to find Cosme, his sister Laura's husband, afflicted by a madness the cause of which no one can discover. Cosme (El otro) relates that while Laura was away on a trip, a man, an exact double of himself, came to the house, and that that other man was in fact he. His body is buried in the cellar. Laura explains that Cosme had a twin, Damián, who also wooed her. Unable to decide between the two, she had left the decision to them, and Cosme had won. Damián married a woman named Damiana, who now arrives in search of her husband, who had left home a month before to visit Cosme. The problem is: which brother is alive, and which is dead? Both women claim El otro, but he is unable to satisfy either one or to free himself. Then Damiana announces that she is pregnant, whereupon Laura gives in before the impetuous fury of the other woman. Meanwhile, El otro has committed suicide. The mystery is never cleared up, and the Cain and Abel conflict goes on, perhaps to continue in Damiana's offspring.