In a world where the seasons last for years at a time the action begins in the unified Seven Kingdoms  of Westeros, as the long summer ends and winter draws near. Lord Eddard Stark is asked by his old friend, King Robert Baratheon, to serve as the Hand of the King following the death of the previous incumbent, Eddard's mentor Jon Arryn. Eddard is reluctant but receives intelligence suggesting that Jon was murdered. Eddard accepts Robert's offer, planning to use his position and authority to investigate the alleged murder.

Meanwhile, on the eastern continent of Essos, the exiled children of House Targaryen, which Robert destroyed to claim the throne, are plotting to return to Westeros and unseat the 'usurper'. To this end, Viserys Targaryen arranges the marriage of his sister Daenerys to Khal Drogo, the leader of 40,000 Dothraki warriors, in return for the use of his warriors in invading Westeros. For her part, Daenerys just wants to find a safe refuge far away from King Robert's assassins and her brother's scheming ambition.

Finally, on the northern-most border of the Seven Kingdoms the sworn brothers of the Night's Watch guard the Wall, a 300-mile-long colossal fortification of ice which has stood for thousands of years. The Watch defends the Wall against the depredations of the lawless wildlings who live beyond, but rumour speaks of a new threat arising in the lands of perpetual winter.