Why is it that so many of the happy-sounding hits of the 1960s such as "Downtown" and "Georgy Girl" become sad if you listen to the lyrics?

That dichotomy is addressed in "Last Night in Soho," which starts like one of those upbeat tunes and, having shifted gears a couple of times in between, ends up somewhere darker and stranger. Taking us on that journey is Ellie (Thomasin McKenzie from "Jojo Rabbit"), a present-day fashion student whose obsession with swinging London of the 1960s mind-melds her with a seemingly carefree, '60s alter ego named Sandie (Anya Taylor-Joy).

Sandie shows Ellie the neon lights and short skirts of Carnaby Street but also the dirty truth beneath the pop-art glamour: Twiggy and Julie Christie may have been the avatars of the era but, like so many things, it was controlled by leering, perverted white men with money. Ellie, who lost her mother at a young age, begins to understand why her mom died by suicide while struggling to solve the disappearance of Sandie, who she believes was murdered.

It's a chaotic movie, shifting from bright comedy to David Lynch-style mind games to Tarantino-esque violent romp to whodunit to horror. As you might guess from that description, there's no way to harness the reckless energy of the story. There are times when "Soho" could give you whiplash, like when you're asked to vibe with a John Hughes-esque romance between Ellie and a fellow student just as the movie pivots to zombies — and I don't mean the Zombies, who had a few of those happy/sad '60s hits themselves.

That can be frustrating but also thrilling. If you get tired of feeling like you always know what's going to happen next in movies, I guarantee you won't experience that with "Soho." You won't be bored and you won't need to fear that director/co-writer Edgar Wright ("Baby Driver") has nothing to say. If anything, he has too much, as evidenced by the credulity-straining final twist, about which it's better not to say much except that it asks a lot of an actor who is outstanding but not a miracle worker.

Wright has cleverly cast Rita Tushingham, Terence Stamp and the late Diana Rigg, three people who actually were around for the swinging '60s. Rigg, playing Ellie's landlady, says of her tenant's obsession with the era: "It's more my time than yours." Their elegant performances balance the shape-shifting elsewhere in the movie and offer subliminal reassurance that not everything we believed about the stylish fun of the '60s was wrong, since the actors, like their characters, made it out alive.

They'd probably agree with singer Petula Clark that "when you're alone and life is making you lonely, you can always go downtown."

But, having lived through exploitative behavior and toxic moneymen, these three survivors are a reminder that it's a good thing to go there with your eyes wide open.

'Last Night in Soho'

*** out of 4 stars

Rated: R for bloody violence, sexual content, drug use and frank nudity.

Release: Wide release.