'Game of Thrones' Premiere: What to Expect from Season 5

— -- Dragons! Dire wolves! White Walkers!

Yes, it's the return of HBO's wildly popular "Game of Thrones," and as season five gets underway tonight, the show's sprawling cast of characters -- and a bunch of new ones -- resume their struggles for revenge, power and control of the Iron Throne of Westeros.

This season is reportedly going to depart from the original books, written by George R.R. Martin, in a number of ways, not the least of which is having some characters who have never met in the books encounter one another. Also, characters who are still alive in the books may be killed, and vice versa.

Here's a look at some of the major characters and their main challenges this season:

--Having killed his own father last season, Tyrion Lannister has escaped King's Landing with Varys, one of the king's advisors. They'll travel across the sea to the cities of Pentos and Slaver's Bay, where Tyrion must use his wits to survive, not having any of his usual Lannister resources, including buckets of cash, to call upon.

--Across the Narrow Sea, Daenerys is struggling to maintain control of the city of Mereen. She's also struggling to control her three dragons, who are bigger, more violent and more defiant than ever.

--Cersei Lannister is furious that she won't be able to take revenge on her brother Tyrion for killing their father, and she's even angrier at the fact that her young son Tommen, who's now the king, is going to marry Margaery Tyrell, which will demote Cersei to Queen Mother. She's also on the outs with her twin brother and lover, Jaime Lannister, who helped Tyrion escape. She tries to enlist a new character, a religious leader played by Jonathan Pryce, to help her politically.

--At the Wall, Jon Snow must decide whether to throw his loyalties behind would-be-king Stannis Baratheon, or Mance Rayder, the leader of the Wildlings, whom Stannis has taken prisoner.

--Young Arya Stark has escaped to the land of Braavos, where she'll be having some truly strange adventures. Her sister Sansa Stark, tired of being a door mat, is now firmly determined to play the game of thrones with her conniving mentor, Petyr "Littlefinger" Baelish.

Meanwhile, we'll travel to a new land: Dorne, home of the late Prince Oberyn Martell: he's the guy who got his head squashed like a melon last season by "The Mountain" while fighting for Tyrion's life. Now, Oberyn's brother, lover and butt-kicking crew of bastard daughters, known as the "Sand Snakes," are thirsty for revenge -- and that's a major plot point for this season. Let the killing -- and the nudity -- begin!