THERE'S A MOMENT midway through Alice Through the Looking Glass that hints at a much darker story, in which the orgy of CG gibberish ceases and Alice (Mia Wasikowska) wakes up from her reverie. She's strapped to a bed in a grim Victorian-era madhouse, with a psychotic-looking doctor (Andrew Scott, Sherlock's Moriarty) threatening to inject her with a nasty-looking syringe. Before any real harm can be done, of course, Alice breaks back into the movie's fantasy world to continue on her quack-a-doodle quest.

That quest—Looking Glass' main narrative thrust—is almost indescribably confusing, an unholy concoction of Lewis Carroll's brilliant nonsense shoehorned into every ass-backward cliché from every cut-rate screenplay-writing night-school class in Los Angeles County. There are moments when the outrageousness and visual cacophony almost push this sequel to Tim Burton's Alice in Wonderland into fits of surreal inspiration. But the horrible storyline—centered on a deeply stupid MacGuffin in the form of time-travel machine called the Chronosphere—and profoundly awful performances from Johnny Depp and Anne Hathaway make this a tough sit.

The threat of Alice's lunacy in that one madhouse scene gives you a glimpse of how director James Bobin (The Muppets) could have turned this into something darker and far more interesting. And the movie is so audaciously weird that it's never boring, exactly: Sacha Baron Cohen, who plays Time, seems to be doing a riff on Werner Herzog (or possibly Christoph Waltz), while Helena Bonham Carter, repeating her conflated role of Carroll's Queen of Hearts and Red Queen characters, is fully committed to the surrounding insanity.

But this is a focus-grouped merchandise machine meant to spawn theme-park rides and fast-food-meal toys. In the correct hands, Alice 2 could have been a sugar-spun confection sailing effortlessly on wordplay and visual invention. Instead, it's a shipwreck.