Karma, they say, is a dish best served cold. In King's Landing, it's a dish served with live birds and a side of poisonous wine. Lucky for us, the cupbearer is TV's biggest twerp. And lucky for us, the poison worked.

It's hard to think of a more satisfying outcome for Joffrey Baratheon, the most reviled character on a show full of characters worth reviling. Joffrey wasn't just a rotten king – he was a monster, plain and simple. A little blonde monster with a sh!t-eating grin.

Who poisoned Joffrey Baratheon? Is this the new Who Shot J.R.? Or Who Killed Mr. Burns? Doubtful, since book-readers already know the answer (and some eagle-eyed viewers will figure it out with a re-watch). But the writers willy surely tease this one out, since it gives the show its pulpiest mystery yet.

Of course, Joffrey dying on his wedding day was no accident. The sequence of events – the strategic cup-dropping, the out-of-nowhere appearance of Dontos – suggests conspiracy. But it's also great storytelling. Joffrey at his most horrible and manipulative – as he was, with his garish mock rendering of the war of the five kings – is also Joffrey at his most vulnerable. When better to watch him croak?

The jury's still out on who hated Joffrey more, and who had the most to gain from his death. So far, the likeliest candidates:

• Tyrion. Number one with a bullet, and not just because Joffrey's dying decree was a finger pointed directly at his despised uncle. Tyrion was acting suspiciously all episode, first by helping Jaime adjust to his new hand, and later by shaming Shae into leaving the city. And Joffrey's outward humiliation of Tyrion – by destroying his wedding gift and mocking him with a show of little people – is just the sort of thing to tip a level-headed man over the edge.

• Sansa. Why would she want her former fiance dead? Hmmmm, let's see: he ordered the death of her father, tortured her in front of his kingdom, held a loaded crossbow to her head, was part of the conspiracy to have her mother and brother murdered, saw her as more of a macabre play-thing than an actual person. I think she has her reasons.

• The Tyrells. The new queen, her brother and her grandmother all have reason enough to loathe Joffrey, and they haven't exactly been mum about it. With Joffrey out of the way, Margaery is free of his sadistic burden, and their family name is all the safer for it.

• Oberyn Martell. You know, the man who just last episode was all "screw Lannisters, I'm here to cause trouble." He has "suspicious as hell" written all over him.

• Dontos. Because Dontos is nobody's fool? I guess?

Belive it or not, some other things happened this episode. Ramsay Bolton, his new girlfriend and Theon "Reek" Greyjoy chased and murdered some innocent girl in the woods because Ramsay is a few fries short of a Happy Meal. Theon's been reduced to his most pathetic state, tilted sideways and talking like a lobotomy patient. Roose sends his son and his "pet" Reek on a mission to find and kill the living Starks: Bran, Rickon and Jon Snow.

Over in Dragonstone, Stannis is still being a mope. After sacrificing his wife's brother to R'hollor, the lord of light, he has a very Stannis-like dinner where everyone is depressed and talking like religious fanatics. It's all pretty boring exposition, but it's good to remember that Stannis and Melisandre are still very much a part of the game.

We also check in with Bran, who's a full-blown warg now, jumping into his direwolf Summer to escape his reality: starving in the snowy northern tundra with Hodor and the Reeds. Apparently Bran can also warg into godswood trees, which he does – and gets a super trippy explosion of visions in the process. It'll be fun to go back and freeze-frame and parse through everything he saw. The most obvious, and menacing, of the tree's teases: King's Landing drenched in the shadow of a flying dragon.