Mystery Street is John Sturges' smart, crisply paced precursor to modern forensic crime shows like CSI and Law and Order complete with all of the inherent weaknesses of the then-fledgling genre, and a few strengths that this film's predecessors mostly lack. The film opens with a gorgeously shot, moody sequence that suggests a typical noir plot in the making: a sleazy, breezy dame (Jan Sterling) who works as a "dancer," seemingly involved in some kind of blackmail thing, making desperate late night phone calls to the guy she's putting the squeeze on, then heading out to make him pay. The set-up is bathed in shadow, and when she ropes in some poor, innocent schlub at a bar (Marshall Thompson), the elements just click. The femme fatale, the innocent in over his head, the nighttime drive she takes him on, heading out along unlit country roads towards a destination she seems very sure of, even as he begins to sober up and realize his mistake. When he's left in the woods alone as she speeds off in his car, can anyone really be surprised? What's interesting is that the film abruptly cuts this seemingly developing plot short; this girl, her blackmail plans, her midnight drive, it's all a dead end, and quite literally at that.
The real meat of the film picks up from this point, reducing the femme fatale to the role of backstory, a prologue that sets up the rest of the action her absence, and her murdered corpse, define the remainder of the story. As for the bulk of the film, as detective dramas go it's fairly satisfying. Lieutenant Peter Morales (Ricardo Montalban) is placed in charge of the case, and to help him investigate the identity and cause of death of the mysterious skeleton that's discovered in the sand dunes off Cape Cod, he enlists the help of the Harvard forensics lab. This must have been excitingly novel back in 1950, and even if the thrill has worn off from repetition, the film is still notable for its originality. Certainly, the methods and scientific tools of criminal investigation had probably never been given such concentrated attention in a Hollywood production before even if sometimes the science itself seems more suspect than some of the suspects. Sturges does his best to jazz up the forensics as much as he can, and in this he's somewhat helped by the occasional bursts of quirky humor from the improbably named Dr. McAdoo (Bruce Bennett), one of a long line of movie coroners and lab men with a streak of gallows humor, though Bennett also gives him more gravity than most.
This kind of perfunctory but nuanced characterization runs throughout the film, which is blessed with a seemingly never-ending parade of memorable bit players who each get their chance to chew some scenery and spit it out again. Poor murdered Vivian is first in line, but she also leads directly to the tiny boarding house where her scheming landlady (Elsa Lanchester) immediately seizes upon her boarder's disappearance as an opportunity to pick up some cash. And once the landlady realizes that the girl is dead, and that she likely knows who did it, then Vivian, who could once never pay her rent, begins to look very lucrative indeed. Lanchester is the unbilled star of the film, stealing every scene she's in with her leering, insinuating tone and what turns out to be a prodigious capacity for greed and thievery. She's a sinister and hilarious figure by turns, and sometimes both at once. Also inhabiting the boarding house is a friendly young woman (Betsy Blair) who at first seems like a bit of a bookish schoolmarm type but soon betrays an edgier side that links her with the murdered Vivian; they're both girls who have seemingly seen a lot and done a lot in their brief lives, and one could easily imagine them switching places under slightly different circumstances. The film is crammed with these characters, and even a burly tattoo artist (Ralph Dumke) who admired Vivian from afar gets a few brief but memorable scenes. Just about the only characters who don't make much of an impression are the ones who should, the poor drunken fool who is soon arrested for Vivian's murder, and his weepy, generic wife (Sally Forrest). These two ostensibly form the core of the film's dramatic tension, but it can't be a coincidence that so much of the dramatic material concerning them happens offscreen, communicated later over a telephone or in expository dialogue if the script doesn't give a damn about them, why should anyone else?
That leaves only the cops, and in a film where the focus and center are continually shifting as characters and subplots keep cropping up, Montalban's stalwart Lieutenant Morales is the closest thing Mystery Street has to a continuous central figure. One of the interesting, if underplayed, elements in the film is its mostly unstated ethnic component. The two cops investigating the case, Morales and his partner Sharkey (Wally Maher), each have thick and distinctive accents: Morales with his smooth Latin accent (he covers the "Portuguese sector" of town usually, a subtle hint of the ghettoization in cities and professions alike) and Sharkey with a mouth-full-of-marbles Boston brogue. In many ways, the ethnic subtext is enhanced by the way that the film mostly ignores it, presenting these two with a matter-of-fact lack of comment about their accents or ethnicities they're simply there, as part of the city and its multiplicity of ethnic identities blending together. There's only one scene in which these tensions rise to the surface, when Morales' immigrant background rubs uncomfortably against the WASP-y privilege of the film's oily villain (Edmon Ryan), an old-money type who can trace his family back several hundred years in America.
As a whole, Mystery Street stumbles more than once, and its plotting is alternately turgid and incredibly clever the audience knows much more than the detectives right from the beginning, and the film is littered with clues that create suspense as the audience wonders when, or if, they'll be found. Interestingly, not all of them are, and some of the best scenes are the ones in which Sturges places Morales tantalizingly close to important information, only to have him pass over it again and again not because he's dull or dim-witted, but because that's the way things go sometimes, and some clues are only obvious to movie audiences conditioned by years of detective thrillers. Not everything works quite as well, and there are many moments when one wishes for another bit of diverting business with Lanchester or Ryan rather than the weepy melodrama of the young couple torn apart, or another tired pseudo-scientific detection routine. But on the whole, Mystery Street remains compelling and interesting even as the films and TV shows it inspired are still trying to endlessly revisit and reinvent its formula over fifty years later.