HBO loves us and wants to keep us happy. That's obviously why they've released this Game of Thrones season-two teaser five months before the show airs.
In this teaser, a grim, determined narrator states his right to the Iron Throne, the chair in which the king of Westeros uneasily sits. We get flashes of the characters we've grown to love, also looking grim. As a teaser, it absolutely works because it piques our interest and leaves us wanting more.
Minor spoilers: The narrator of this little gem is Stannis Baratheon, King Robert's younger brother. He's claiming the throne ... but it wouldn't be Game of Thrones if he were the only wannabe king. Expect political intrigue, political backstabbing ... and general backstabbing and frontstabbing.
And dragons. Don't forget Danaerys' dragons.