Despite the biblical prohibition on sexual relations between half-brothers and sisters, (Leviticus 18:11) Amnon had an overwhelming desire for her. He acted on advice from his cousin, Jonadab the son of Shimeah, David's brother, to lure Tamar into his quarters by pretending to be sick and desiring her to cook a special meal for him. While in his quarters, and ignoring her protests, he raped her, then had her expelled from his house. King David was angry about the incident, but could not bring himself to punish his eldest son, while Absalom, Amnon's half-brother and Tamar's full brother, nursed a bitter grudge against Amnon for the rape of his sister.
Two years later, to avenge Tamar, Absalom invited all of David's sons to a feast, then had his servants kill Amnon after he had become drunk with wine. (2 Samuel 13)
The Spanish poet Federico García Lorca wrote a poem about Amnon's rape of his sister Tamar, included in Lorca's 1928 poetry collection Romancero Gitano (translated as Gypsy Ballads). Lorca's version is considerably different from the Biblical original - Amnon is depicted as being overcome by a sudden uncontrollable passion, with none of the cynical planning and premeditation of the original story. He assaults and rapes Tamar and then flees into the night on his horse, with archers shooting at him from the walls - whereupon King David cuts the strings of his harp.