A Clash of Kings by George R. R. Martin

A Clash of Kings (A Song of Ice and Fire, Book 2) - Queen Cersei claiming that her son Joffrey is the eldest trueborn son of the late King Robert rules from the Iron Throne.  However, her claim is not unopposed.  Several people, including King Robert's brothers know that Joffrey is Cersei's son by her brother Jamie Lannister. Stannis Baratheon, the eldest of Robert's living brothers, claims he his king by familial succession.  Renly Baratheon claims he is the rightful king because he is more popular and would make the better king.  Robb Stark, eldest son of the late Hand of the King, Eddard, claims kingship of the north.  And Daenerys Targaryen, the sole survivor of King Aerys II, claims she is Queen of the Seven Kingdoms and plans to regain the throne for her family.

While war reigns to determine who is king where, Tyrion Lannister plots for his own gain while performing his duties as the King's Hand.  Arya Stark, posing as an orphan boy, tries to work her way back to Winterfell.  Sansa Stark, forced to stay at King's Landing as Joffrey's fiancee, plans to escape. Jon Snow, Eddard Stark's bastard son, as a member of the Night Watch, joins the search for the missing black brothers north of the wall.  Meanwhile, the Greyjoys scheme to takeover the north while everyone else is fighting in the south.