Heading into its fifth season, HBO’s Game of Thrones has accrued some tremendous assets—and a few daunting challenges. On the plus side of the ledger, the show has a loyal global audience, an exceptional cast, and the full backing of its network, HBO (as evidenced by this year’s larger-than-ever budget). On the minus side, last season’s plots and counter-plots resulted in the deaths of several of the best secondary characters the show has had (Tywin Lannister, Oberyn Martell, the Hound, Ygritte). More important still, the last two seasons were based on the third, and best, of George R.R. Martin’s A Song of Ice and Fire novels. Season five, by contrast, draws from Martin’s spiraling, frequently maddening, fourth and fifth books. Up until now, the challenge for showrunners David Benioff and D. B. Weiss has been not to break anything. This season is the one in which they need to start fixing Martin’s mistakes.

The good news is that, based on the evidence of the first four episodes, they have accurately diagnosed most of the ills befalling their source material. The (perhaps) bad news is that it’s not yet clear how fully their proposed remedies will succeed.

In any case, make no mistake: This is the season that Benioff and Weiss fully inherit ownership of Game of Thrones from Martin, as they begin charting their own course to an unprecedented degree. They’ve been practicing for this moment for a while with assorted tweaks and deviations, and they seem to have been getting better. The encounter between Brienne and the Hound in the final episode of last season was their best alteration to date—and one that fixed flaws with both characters’ storylines in the books.

This season, Brienne continues to be given original things to do, and new subplots have also been provided for Sansa and Jaime. Moreover, there’s substantial evidence that Tyrion’s narrative, which bogged down hopelessly on the page, has been accelerated to the point where he will have gotten farther by season’s end than he ever did with Martin. (Those not averse to a spoiler regarding what this means can have a look at this on-set photo, which has been making the rounds for a few weeks.)

A quick refresher for people who may have forgotten where things stood at the conclusion of last season. At the Wall, Stannis Baratheon’s army routed Mance Rayder’s wildling horde and saved Jon Snow and the Night’s Watch from being overrun. Farther south, Brienne ran into the Hound and Arya Stark; while the former two fought (to evidently fatal consequence for the latter), Arya slipped away, ultimately boarding a ship for Braavos with the coin given to her by faceless assassin Jaqen H’ghar. Sansa Stark and Petyr "Littlefinger" Baelish were still in the Eyrie, where the latter had assumed control after hurling his troublesome new wife, Lysa Arryn, out the Moon Door.

In King’s Landing, Tyrion Lannister escaped his death sentence with the help of his brother Jaime and the erstwhile Master of Whispers Varys; on his way out, he strangled his ex-lover Shae and crossbow-bolted his father, Tywin, on the john. He was last seen in a box on a ship, headed for parts unknown. Finally, across the Narrow Sea in Meereen, Daenerys Targaryen had locked up her disobedient dragons (at least the two she can find), as she underwent another rendition—it won’t be her last—of “It’s Not Easy Being Queen.”

So what comes next? Well, without giving away details, Tywin’s death will prove immensely destabilizing—as it should, given that he had been among the most powerful men in Westeros for decades in one capacity or another: Hand to three kings, father of the queen, richest lord in the Seven Kingdoms. In King’s Landing, his absence means there’s no grownup to check the hasty, vindictive impulses of his daughter Cersei, who feuds with Margaery Tyrell over her son, the new boy-king Tommen. She also makes a profoundly ill-advised choice of candidate (played by newcomer Jonathan Pryce) to be the new High Septon of the Faith.

Farther afield, there is a sense among competing houses that the Lannister grip on power is greatly diminished with Tywin’s passing. It helps not at all that the Lannisters have acquired a new enemy—or, rather, confirmed an old one—in the southern reaches of Dorne (beautifully filmed, incidentally, in Spain, a new locale for the show). Prince Oberyn Martell, killed by the Mountain last season in a trial by combat, was a Dornish hero. And while his elder brother, Doran (Alexander Siddig), is slow to anger, Oberyn’s paramour Ellaria Sand and his three illegitimate “Sand Snake” daughters (Keisha Castle-Hughes, Jessica Henwick, and Rosabell Laurenti Sellers) are burning for revenge.

In the North, Stannis, the Night’s Watch, and the wildlings need to sort out their relationships to one another—and, beyond that, their postures toward the new Warden of the North, the cold-blooded Roose Bolton, and his demonic son, Ramsay. In Braavos, Arya begins her training to become—well, we’ll see what she becomes. Daenerys, as noted, still has her hands full in the ex-slaver city of Meereen. Brienne and Pod continue their odd-couple bickering as they search Westeros for the missing Stark girls. And Littlefinger is hatching a brand-new plot, with Sansa at the center of it.

As for Bran Stark? He has the season off. Having reached the three-eyed raven at the end of last season, he's going to be further discovering his warg-ish abilities off-screen, returning next year for season six. It’s a sensible move by Benioff and Weiss, even if there’s a danger that Isaac Hempstead-Wright, who plays Bran, will look 30 by the time we next see him. (Would that the showrunners had done likewise with Theon in season three; in the books, his torture and mutilation at the hands of Ramsay—easily Benioff and Weiss’s biggest mistake to date—were only heard about secondhand.)

The season starts relatively slowly, but the first four episodes gradually accelerate, each one perhaps a little bit better than the one before it. There’s no early shocker on a par with the Purple Wedding, but the body count, unsurprisingly, is still higher than zero. Benioff and Weiss have promised that they will be killing off characters who did not die in the books—an experiment that began last season with the death-by-wight of Jojen Reed—which should keep even the most avid book reader on the edge of his or her seat. And while the showrunners have also overtly sexualized a few characters’ relationships (again, unsurprisingly), so far the show seems mostly to be avoiding its worst carnal excesses.

As always, the ongoing machinations in King’s Landing are a particular pleasure. And things in the North are getting more interesting as well, thanks in no small part to Stephen Dillane, who has grown nicely into the role of Stannis. If anyone can offer the show a little Tywin-like gravitas this season, it will likely be him. Benioff and Weiss have also been kind enough to write fan-favorite Bronn—who’s essentially out of the books by this point—into one of their new subplots. (Though she hasn’t yet appeared there’s the promise of more of Diana Rigg’s Lady Olenna as well.) And it’s extremely nice to see Sansa—finally!—have something more to do than be passively victimized, even if I have some misgivings about the storyline Benioff and Weiss have cooked up for her.

I’m a touch nervous about the goings-on in Dorne as well. In the books (at least so far) the Sand Snakes have played only a peripheral role, but Benioff and Weiss seem to be setting them up as a trio of female action heroes, a kind of Deadly Viper Assassination Squad for the sword-and-sorcery crowd. Indeed, most of the early signs suggest that the showrunners’ new material will take Game of Thrones in a more cinematic, less literary direction, in which outsized daring is substituted for the quiet cunning that characterized Martin’s work. The scale of the show has certainly never been grander, with beautiful introductions of cities on both sides of the Narrow Sea and the showrunners’ promise of a battle scene late in the season that is larger than anything they’ve undertaken before. Plus, Dany’s dragons are growing up nicely.

Whether this more cinematic vision will ultimately succeed as well as the earlier, book-centric seasons is not yet clear. (Spencer Kornhaber, Amy Sullivan, and I will again be following as it unfolds episode by episode at the Game of Thrones roundtable.) But given the issues of pace and focus that bedevil Martin’s later novels, Benioff and Weiss’s impulse to both compress and juice up the material makes eminent sense. The result is a season of Game of Thrones that promises to be bigger than ever.