Do not read on unless you’ve seen “The Riddle of the Sphinx,” the fourth episode of the second season of HBO’s “Westworld.”

“The Riddle of the Sphinx” marks “Westworld” co-creator Lisa Joy’s first episode as director. So let’s get two things out of the way. First, this is probably the best, most ambitiously directed episode of the series, and the more Joy directs, the better off this show will be. Second, the opening shot, one of the most beautiful and affecting in “Westworld” history, is derivative enough that it merits an asterisk. “Play With Fire” is hardly the most abused Rolling Stones song in terms of over-licensing, and “The Darjeeling Limited” is hardly the strongest film in Wes Anderson’s catalog. But come on.

Anyway, the scene still works (for what it’s worth, the song actually makes more lyrical sense here than it does in the Anderson movie — where, like most things Anderson, it’s just there for pretty), opening with one long, panning shot of what looks like an apartment lifted off the set of “Legion” or “Mad Men” as the early Stones song plays.

We see Mr. Delos, and it’s obvious that we’re in the pre-MiB William era again. Last season, William seemed like a breakout role for Jimmi Simpson, who has made a career playing creeps. It was nice to see him get a chance to do earnest, and he did it well. But as season two calls on Simpson to show his character evolve into Ed Harris’ Man in Black, he is once again free to let his creep flag fly. His casting makes more sense than ever.

There are three flashbacks to this apartment, which, in the second, we learn is a cell in a “Westworld” facility. Here, super-seret experiments are taking place — attempt after attempt to have Mr. Delos’ (yes his name is James, but “Mr. Delos” is more fun) mind transferred into a host. Years of attempts yield only incremental progress. In the second flashback, a once-promising failure ends in cleansing fire, for no obvious reason other than that it looks cool, which is more than fine. There is a lot that looks cool in this episode, with Joy borrowing from not just Anderson’s psychedelia, but also horror and western aesthetics with more flair than the series has ever demonstrated. It’s the “Westworld” we deserve.

Which is weird, because it’s not the “Westworld” we know. “The Riddle of the Sphinx” is the first episode without a Maeve or Dolores storyline, ceding the floor to the show’s leading male characters — Bernard and MiB William. Oh, and Elsie.

Yes, Elsie’s back, looking not bad for having been left chained in a cave for days — weeks? — with, as she puts it, nothing but energy bars and a bucket. It was Bernard, under Ford’s spell, who put her there. Elsie is understandably less than thrilled to see Bernard again when Clementine drags him into the cave with her, all apparently part of Ford’s plan.

The Bernard-Elsie stuff has two things going for it. One is an ingenious device Joy uses to reveal not only that Bernard has been here before, but also what he did here. It’s a safe bet, when we see the bodies inside the facility, that they were the work of Bernard in Ford-control mode, but, Joy’s method of melting past into future makes what might otherwise seem obvious instead appear cleverly hidden in plain sight.

When, later, Bernard and Elsie discover RoboDelos gone berserk, slicing himself up, it’s a little confusing, but genuinely terrifying. That said, the idea that Elsie would walk in on that scene and start talking to whoever was inside is not the most plausible thing, given that survival and escape are her primary goals.

Even less plausible, but kind of enjoyable, is the hint of redemption for MiB William. It makes sense that Harris’ William would have a heart in there somewhere, given his white-hat beginnings. But why would the plight of the hosts, whom MiB William has raped and killed who knows how many times, suddenly move him? MiB William has double crossed Lawrence before. Why is now different?

Possibly because the stakes are different. The violence that Lawrence’s neighbors face at the hands of the Confederados feels more consequential than the violence the hosts suffered in season one, because we know now that there is no infrastructure for cleaning them up and getting them back online. Death in the new Westworld is the true death. Maybe. We don’t actually know. But it could be.

MiB William is reunited with Lawrence’s daughter, a far creepier and more effective mouthpiece for Ford’s ghost than Little Lord Robert, who always felt like he had walked out of an overly ambitious commercial for cellular phones or financial services. MiB William is then reunited with — drumroll — his own daughter.

Grace (as we’ll call her, because IMDB does) has been one of this season’s best additions. If a show ever needed a swashbuckling female character who talked kind of like Holly Hunter (or am I just wanting to hear that?), this show did. The shot at the episode’s end, when MiB William, Lawrence, and Lawrence’s cousins ride into the sun, only to have Grace ride up on them, feels like a shot from a big Western, with promises of adventures to be had.

Some other thoughts:

• “Do the Strand” by Roxy Music? Song selection has improved this season.

• The episode’s title is a reference to the themes of aging and dying that William and Mr. Delos wrestle with, if that’s the sort of thing you care about.

• I guess being prisoner in a cave took all the wisecrack out of Elsie. She was much-needed comic relief in season one, but unlike Sylvester or Lee, her character always felt forced or out of sync with the rest of the show. It will be interesting to see what’s done with her now, as Joy and fellow showrunner Jonathan Nolan have clearly rethought some things.

• Seriously, if all “Westworld” does is launch Lisa Joy’s directing career, it will have been worth it.