People are dying- the King of the Iron Isles is dead, his throne up for grabs, and Lord Tywin Lannister has been found dead in King's Landing. Meanwhile, Tyrion, accused of killing King Joffrey, roams free and the Queen Regent, Cersei, sends spy after spy out after the man who killed her precious son. Arya and Sansa Stark, each assuming the other dead, have found help, Sansa wearing the name Alayne Stone.
Unlike the three that came before it, which, despite being good books, read rather slowly, this one read rather quickly. Of course, that's quickly for a nine hundred page book... Anyway, this is a good read, a bit different from the previous books in the series but still a fitting sequel.
I highly recommend you read the first three books in the series first, because otherwise you will be lost.