Grade: A

After expending entirely too much effort on big-budget nonsense like “Blade,” “Hellboy,” “Pacific Rim” and “Crimson Peak” (not to mention the TV series “The Strain” and the flop thriller “Don’t Be Afraid of the Dark”), Guillermo del Toro has returned to his roots in offbeat, highly personal cinema with his best film in a decade—ever since “Pan’s Labyrinth.” While still feeding into del Toro’s love of the genre movies he adored while growing up, “The Shape of Water” proves a nostalgia trip with real emotional resonance, a fantastic fable of outsiders pitted against a cruel world that makes its viewers think as well as feel.

The film can be briefly described as a romance between the Creature from the Black Lagoon and a mute maintenance worker, but that would sell it short. In 1962, as the Cold War rages, an amphibian man (limned, in a remarkable “creature” suit, by Doug Jones) has been captured by the U.S. government and brought to a facility in Baltimore, where he is guarded—and mistreated—by a brutal federal agent named Richard Strickland (Michael Shannon) while being examined by the far more sympathetic Dr. Robert Hoffstetler (Michael Stuhlbarg). The goal is to determine how the creature’s anatomy might provide clues that might facilitate human abilities in space travel.

It’s top secret, hush-hush stuff, of course, but when Strickland suffers an injury that requires aid (as well as a cleaning job), two of the maintenance staff are allowed into the inner sanctum—mute, mousy Elisa Esposito (Sally Hawkins) and her sassy buddy Zelda (Octavia Spencer). Elisa catches a glimpse of the melancholy creature, and feels it a kindred spirit of sorts. Using food and music, she secretly coaxes it into a relationship that blossoms into an interspecies friendship, and then something more. And when Strickland and his super-hawkish military superior General Hoyt (Nick Searcy) decide that the experiment should be terminated with extreme prejudice despite Hoffstetler’s objections, Elisa decides to intervene, enlisting her reluctant neighbor Giles (Richard Jenkins) to assist her in pulling off a great escape. (Others will eventually take roles in the mission as well.)

Given that this is a del Toro film, there are some elements—Strickland’s early accident and its aftermath, an impromptu lunch the creature grabs in Giles’s apartment, a last-act confrontation that takes a violent turn—that are somewhat gruesome. But they’re embedded in a rich, mesmerizing romantic fantasy with a heartfelt streak that extends to all of society’s outcasts. Visually it’s as gorgeous as “Crimson Peak” was, though the perfectly detailed color palette this time emphasizes blues and greens as opposed to the reds of the earlier picture (it’s impossible to overpraise the work of production designer Paul Denham Austerberry and cinematographer Dan Lausten), and aurally it’s equally magical, thanks not only to the period pop songs used as plot pegs but to the lovely, amazingly varied music by Alexandre Desplat, which stands out even among his long train of outstanding scores.

The centerpiece of “Water” is, of course, the relationship between Elisa, played by Hawkins with ineffable charm) and the amphibian man (with Jones bringing poetic grace to his every move). They are the ultimate unlikely couple, both of them isolated from society in distinct ways but drawn together by a bond of differentness. But the other characters are outsiders, too. Giles, beautifully played by Jenkins, is a gay man fired from his job at an ad agency that he’s desperately trying to win back; and when he attempts to make contact with the counterman at a pie shop (Morgan Kelly), he’s cruelly rebuffed. The same clerk refuses to serve African-American customers, which throws into relief the position of Zelda (played with typical energy by Spencer) at a time when casual racism, in contrast to today’s hidden variety, was rife. (Prejudice of any sort, in fact, is equated with some degree of dehumanization, which reaches its ultimate point in, for example, Strickland’s attitude toward the amphibian.) But even Hoffstetler, whom Stuhlbarg endows with a weary dignity, turns out to stand apart while Strickland himself, to whom Shannon brings a demonic degree of malevolent intensity, finds himself alone in the end.

As so often in del Toro’s films, one can’t help but note the director’s own cinematic obsessions at work. Elisa and Giles not only share a love of old Hollywood musicals, which they watch together on television—a plot thread that leads to a rhapsodically outrageous dance sequence that trumps even those in Herbert Ross’s sumptuous remake of Dennis Potter’s “Pennies from Heaven”—but just happen to live above a creaky old theatre where CinemaScope biblical epics play to near-empty houses.

But while such references could seem merely precious or cute, in this case they bring an added layer of feeling to a wondrous adult fairy-tale played out with impeccable cinematic control. “The Shape of Water” is a magical and moving experience.