King Robert Baratheon of Westeros (Mark Addy) enjoyed winning his crown more than he does wearing

it. When he was young and strong, he overthrew the sadistic regime of Aerys Targaryen, "the Mad King."

Now he's middle-aged and fat; married in a loveless political alliance to Queen Cersei (Lena Headey),

daughter of the wealthy, cunning Lannister family; and sitting on the Iron Throne, forged from the swords

of vanquished foes and literally painful to occupy.

Embittered by success, Robert passes an afternoon reminiscing with one of his guards about his first kill

in battle: a highborn boy who begged for his life as Robert raised his war hammer. "They never tell you

how they all s--- themselves," Robert says with a grim laugh. "They don't put that part in the songs."

HBO's ambitious, visually stunning Game of Thrones puts that part in the songs. Like The Lord of the

Rings, Thrones (which debuts April 17) is set in a quasi-medieval world with a mythic history, riven by

conflict. But there are no singing elves, tubby halflings or noble wizards. There is a dwarf — crafty lordling

Tyrion Lannister (Peter Dinklage) — but he frequents whorehouses, not Bilbo's hobbit hole. And there

are hints of magic, mostly in the past, but Westeros is (or believes it is) a postmagical world. Where

centuries ago there were dragons and sorcerers, now there are only steel and blood and the cheap

grubbings of men.

As did HBO's western Deadwood and historical drama Rome, Thrones takes a familiar, oft-romanticized

genre — epic fantasy — dirties it up and blurs the moral lines. Based on a millions-selling series of novels

by George R.R. Martin (whom TIME's Lev Grossman called "the American Tolkien"), Thrones is

unsentimental and often brutal. It's also shaping up to be the most immersive grownup adventure TV has

produced since Lost.

Thrones is a complex narrative with a simple theme: power — scheming for it, keeping it and suffering

from it or the lack of it. (Warning: plot-expository roadwork ahead, next three paragraphs!) After the

King's Hand (a kind of Prime Minister) dies suspiciously, Robert calls on war buddy Eddard "Ned" Stark (Sean Bean), the lord of castle Winterfell in the forbidding north, to replace him. Ned reluctantly agrees,

moving his family to the capital, King's Landing, where he finds a mystery — was the Hand murdered,

and if so, why? — and a nest of spies and intrigues that challenge his simple, direct morality.

That morality, it turns out, isn't absolute: Ned has a bastard son, Jon Snow (Kit Harington), preparing to

join the Night's Watch, a kind of foreign legion that guards a massive ice wall on Westeros' northern

frontier. The Wall was built thousands of years ago to keep out spectral creatures of the winter called the

white walkers. In Westeros, seasons can last decades, and in the epic winters of old, the walkers preyed

on the continent. But that was generations ago. Now, in the midst of a long summer, most people no

longer believe in the "snarks and grumkins" whom Jon is pledging himself against (though we get a

glimpse of the horrors beyond the Wall in a horrific prologue).

Elder Stark son Robb (Richard Madden) Courtesy HBO

Meanwhile, across the sea to the east, two exiled Targaryens plot a return to power. Viserys (Harry Lloyd)

is an arrogant fop; styling himself after his ancestors who used now extinct dragons to conquer Westeros,

he calls himself "the Dragon" (an honorific that from his lips sounds as affected as "the Situation"). He is

marrying off sister Daenerys (Emilia Clarke) to Khal Drogo (Jason Momoa), chief of the Dothraki, a clan

of Mongol-like horsemen who Viserys hopes will carry him to the Iron Throne.

Thrones' visual language is Old High Geek — dragon skulls, heraldry, leather and chain mail — but its

psychology is bluntly realistic, a reaction against fantasy clichés like the struggle between absolute good

and evil. Seeming villains show scruples, seeming heroes are compromised, and moral rigidity is a fatal

flaw. (In one duel, a knight is slain by a street-brawling mercenary. "You don't fight with honor!" complains

an onlooker. "No," the mercenary agrees dryly, indicating the corpse. "He did.")

Martin, interviewed near his home in Santa Fe, N.M., says his novels are a response to the fantasy trope

that virtue alone wins the day. "A good man is not always a good King," he says. "And a bad man is not

always a bad King. Probably the best man to serve as President in my lifetime was Jimmy Carter — the

best human being, but he was not a good President. General goodness did not automatically make

flowers bloom."

Thrones' plot is even more complicated than its morality; Martin's books are leviathans, each one adding

layers of conflict. Westeros has millennia of history, distinct religions and cultures and a vast geography. There are dozens of major players scattered across thousands of miles. Several lead characters are

children who experience events and emotions harsher than anything encountered on a Quidditch field.

And did I mention the 700-foot wall of ice?

Martin, who was a TV writer in the '80s on Beauty and the Beast and a remake of The Twilight Zone,

believed his story was unfilmable. He was convinced otherwise by the possibilities of HBO — which

accommodates not just the story's sex and blood but also its moral ambiguity — and a pitch from

producers David Benioff and D.B. Weiss, who wrote much of the first season. (Martin scripted the eighth

episode.)

One of many cavalry-heavy scenes Courtesy HBO

Benioff and Weiss tamed a narrative dragon, editing deftly (beyond an exposition-burdened pilot) but

staying remarkably faithful. Their adaptation, shot in Northern Ireland and Malta, makes every second

count, starting with the ingenious title sequence, in which a map of Westeros, a handy visual aid for

newbies, comes to animated life.

Their story is more than an elegant machine; it captures the elegiac tone of a battle to rule a fallen world.

As the reluctant warrior Ned, Bean has a weary honor, set off sharply by the cynicism of the

golden-haired, deep-pocketed Lannisters — especially the Queen's brother Jaime (Nikolaj

Coster-Waldau), a handsome knight of flexible loyalty. And the show's fantastical premise has timely

resonance: a world whose seasons are out of balance, where houses squabble while laughing off an

existential threat. The visuals enlist CGI sorcery to build towers and vistas (dizzying, if occasionally too

airbrushed-looking), but the real achievement is the design, which weaves European, Mediterranean and

Asian elements into a familiar but exotic culture. This Game feels fully assembled out of the box.

The eastern-continent scenes, however, suffer from a kitschy orientalism. The Dothraki are painted

savages whose furnishings look as if they've plundered a Pier 1 Imports, and the dialogue here is

especially stilted. (There is also one too many uses of the "have some guy explain the backstory while

nailing a whore" device.) But as exiled Princess Daenerys assimilates and gains confidence, her story

line matures with her. And the Westeros plots are an enthralling mix of palace intrigue, murder mystery

and mythology, sold by strong casting. Standouts include the droll Dinklage, playing an intellectual in a

warrior culture, and Maisie Williams as Stark's spunky daughter Arya, who chafes against the expectations of girls. Thrones is deeply conscious of its world's social and class structures and blunt

about the price of rebelling against them.

A wary, weary King Robert Courtesy HBO

If Thrones survives, it will share the high-class problem of popular, sprawling, mythology-heavy series

like Lost: Can it stick the landing? (Martin, a Lost fan, hated its spiritual finale: "They left a big turd on my

doorstep.") Martin, 62, has written four of a planned seven novels; the fifth is due in July, six years after

its predecessor. He says he can keep pace with HBO if — a big if — it devotes two seasons to the

massive third volume and three in total to the fourth and fifth (whose narratives overlap), as he hopes. If

not? "Then yeah, they may catch up with me."

But it's hard to resist taking the uncertain plunge. Watching Game of Thrones is like falling into a

gorgeous, stained tapestry. This epic, unflinching fantasy noir takes our preconceptions of chivalry,

nobility and magic and gets medieval on them.