Starring Sally Hawkins. In English and Russian, with English subtitles. Rated 14A

Guillermo del Toro’s latest is a virtuosic love letter to classic cinema of multiple eras and genres. It’s a shame, then, that it’s so lacking in substance and coherent purpose.

U.K. great Sally Hawkins, whose singsong voice is one of her defining characteristics, is terrific as Elisa, a mute (not deaf) woman who works as a cleaner at a government installation in an unnamed city during an unspecified moment of the Cold War. Judging from the prevalence of automobile fins and talking-horse-type sitcoms on the boob tube, it’s the start of the ’60s, although the soundtrack music leans toward the ’30s.

For a top-secret bunker, Elisa’s workplace sure is awash with low-security employees, including our hero’s protective pal Zelda, played by Octavia Spencer, who must be tired of being the sassy help by now. Elisa lives in a beautifully crumbling art-deco building, over a gorgeous movie palace that shows Bible epics and sci-fi specials to hardly any customers. (The Shape of Water was shot in Toronto, with Massey Hall and the Elgin Theatre heavily featured.) Her next-door neighbour is a reclusive commercial illustrator (Richard Jenkins, perfect at his many throwaway quips) who seems to have been sidelined for being gay.

Thus, we’re handed a coterie of marginalized people even before the introduction of a marvellously strange water creature, probably hailing from a black lagoon. If Doug Jones’s lithe amphibian presence reminds you of the Hellboy movies, that’s because he played a similarly aquatic entity in that del Toro series. And, as in Pan’s Labyrinth, there is a fascistic tormenter here, in the form of Michael Shannon’s cruel enforcer, who of course thinks the thing (as in Howard Hawks’s The Thing) would serve science and the USA better on the operating table.

An in-house scientist, played by Michael Stuhlbarg, sometimes speaking fluent Russian (hint, hint), disagrees. So does Elisa, who views the blue-green-algae dude as an objet d’amour. This is where the movie goes weird, since its storybook imagery and cartoon characters set this up as a children’s tale. You don’t expect nudity and extreme violence after watching a Shirley Temple and Bill “Bojangles” Robinson scene in the background. That dichotomy is del Toro’s specialty, perhaps, but it bends this Water too far out of shape.