Lost Girls is an adaptation of Robert Kolker’s book of the same name, which explores one of the most enigmatic, dispersed and sprawling true crime narratives in recent American history – LISK, or the Long Island Serial Killer. The crux of this story revolves around Shannan Gilbert, a 24-year old woman from New Jersey, who was working as an escort in Oak Beach, on the Long Island Shore, when she abruptly ran away from both her client and driver and disappeared into the dunes. The police only searched for her after considerable pressure from her mother Mari, played here by Amy Ryan, but what they found in the dunes was more than anyone expected – a series of bodies, placed at regular intervals, presumably by a serial killer. Some of the bodies were identified, some remain unidentified to this day, and some stretched back to 1996. Discovery of another burial site on the Ocean Parkway, with a different modus operandi, suggested a second killer might be involved in the case, which remains unsolved.

While Kolker’s book is very sympathetic in its efforts to acknowledge all the known victims in this case, and their individual stories, it didn’t quite contain the sprawl and aporia in this enigmatic narrative as effectively as the Crime Junkie podcast episode where I first learned about it. By contrast, director Liz Garbus has a deep pedigree in true crime documentaries, and a better instinct for how to tell a true crime story. Building upon Michael Werwie’s script, she brings a real structural ingenuity to the way she translates this dispersed case into such a tight feature film. In fact, Lost Girls often feels closer to a true crime text than a fictional film, due to the economy and focus of its storytelling, which remains very close to the facts and intercuts the key scenes with small snippets of real news footage. Unlike the book, Garbus focuses mainly on a single vanishing – Shannan Gilbert – and only gives us a glimpse of this event in the opening credits, leaving us to follow Mari as she pieces it all together in real time.

That’s a great move, since this is the kind of case that you need to follow, step by step, in a piecemeal fashion, to really appreciate the strangeness of it all – and to really feel the bizarre coincidences and serendipities that drove the main avenues of the investigation. Seeing it all unfold in this fragmented way also cements the film as part of a more recent subgenre of true crime – stories that focus on the victim-blaming and perceived expendability of sex workers who fall prey to serial killers. During the first act, the main impediment that Mari faces is the continuous reference to “girls like this” and the “high risk environments” that (implicitly) justify their murders. Time and again, we hear the refrain of “Shannan Gilbert, prostitute” as Mari grows more restless with the classism of the Oak Beach gated community. It took police an entire hour to respond to Shannan’s emergency call on the night she vanished – her last known communication – but only twelve minutes for police to respond to the “Stepford Wives” who call up to report Mari once she starts to embark on an investigation of her own.

This determination to do right by her daughter naturally brings Mari into contact with the mothers of the girls found in the dunes. A great deal of the film is driven by the dynamic between Mari, whose daughter still hasn’t been recovered, and these women, along with the looming question of whether their experiences are the work of a single killer. Garbus introduces these women organically while still realising that this story is best told through one character, capturing their solidarity even as she retains her focus on Mari as their unofficial ringleader. Once again, this is a significant improvement on the book, which often hesitated about whether to choose a protagonist or emphasise the experience of each victim.

However, the most dramatic element of Garbus’ adaptation is the way she folds these disparate events into a broader Long Island Gothic. Much of the film alternates between New Jersey, where the Gilberts live, and the Ocean Parkway, especially in the second half, when Mari seems to be continually commuting between the two. Yet this shoreline is quite a featureless landscape, and thus difficult to capture in a single shot or sequence, even with the aid of Netflix’s signature drone shots. For that reason, Garbus sets out to evoke this landscape through palette and composition, styling the whole film so that it always feels as if we’re glimpsing the Long Island shore through a windscreen in the midst of winter. Not only does the parched colour scheme partake of the sparse bleakness of the dunes where the bodies are found, but the cinematography has a slightly tinted quality, fusing screen and windshield.

It thus feels as if a vast void is crowding in on every scene, thanks to  Garbus’ constant recourse to vacant spaces, occluded perspectives, extreme close-ups and bleary lighting, all of which work to capture the opacity and obscurity of this case – along with the brooding presence of the killer, who most likely has watched the film by now. There’s an eerie contrast between the hi-def Netflix “look” and the blankness of this particular landscape, which remains inscrutable to even the most probing and precise drone shots. That tension reminded me of the recent reboot of Unsolved Mysteries, which also takes the Netflix drone “look” to its forensic and aesthetic conclusion, by presenting us with cases that cry out for – but also resist – the aerial perspectives that have become the streaming service’s stock in trade. In fact, Lost Girls could almost be a special episode of Unsolved Mysteries, composed entirely of re-enactments, and often recalls Garbus’ recent direction on I’ll Be Gone in the Dark as well.

The blankness of the dunes thus becomes a cipher for the eerie aporia at the heart of this case – the moment at which Shannan entered the dunes. Since the case remains unsolved, Garbus can only evoke this possibility, through a lurid green light that looms on the fringes of her mise-en-scene, an alien luminosity on the very edge of things. This green light blooms briefly in the closing act of the film – first in the form of a strobe light at a police party where Commissioner Richard Dormer, played by Gabriel Byrne, glimpses the possibility of a police cover-up; then in the form of a roadside art deco structure (I couldn’t figure out where it was) that Mari glimpses on the cusp of the marsh search that eventually recovers Shannon’s body.

Writing and directing the third act of a film about an unsolved case is a real challenge, so it’s a testament to Werwie and Garbus how well it all comes together here. For one thing, and despite the ambiguity, Mari and Dormer come up with a clear suspect, which gives the final act a propulsive energy that allows it to stay true to Shannan without descending into the dourness that often characterises a certain strand of victim-centred true crime. For another thing, Mari and Dormer are both great foils to an unseen killer and an unresolved case, partly because both characters are themselves unresolved, and partly because Ryan and Byrne quietly slip in two of their best performances in the last ten years. With those two innovations in place, Lost Girls can end boldly – with the discovery of a body that resolves the vanishing, but not the case, which resonates brilliantly through this consummately tactful adaptation.