The US-funded series Game of Thrones is based on a series of fantasy novels called A Song of Ice and Fire by George R.R. Martin. The first book was published in 1996 and they have been bestsellers ever since. Martin is now writing the sixth book in the series and there are plans for more, so we can expect a few more seasons of Game of Thrones too.
The series is set in the imaginary lands of Westeros and Essos. The main action is around who has control of the Iron Throne of Westeros; this is under constant attack, both from within and without. Westeros is under threat from its northern border, which has to be constantly guarded from supernatural enemies, and from the continent of Essos where Daenerys, a claimant to the throne, is building up a force to try and take back the throne which was forcibly taken from her family. The story is inspired by the wars of France and England in the middle ages.