LOST GIRLS: Netflix original scores with strong performances and a solid message

* * * (out of four)

If you watch the terrific new Netflix thriller “Lost Girls,” it’s important to remember that the film is based on an actual case which remains unsolved.

So you won’t find the lurid plotting or tidy resolutions of so many mysteries and crime films; nonetheless, “Lost Girls” is utterly gripping from start to finish.

In part, that is due to a bevy of fine female performances, highlighted by Amy Ryan as a desperate suburban mom whose 20-something daughter disappeared in distressing circumstances.

That young lady’s name was Shannan Gilbert, a sex worker who advertised on Craigslist and who is first seen in this film as she was last seen in life: running crazily down a desolate Long Island highway at night -- and just as crazily refusing to get in the car with her imploring driver.

When nothing else is heard from Shannan, her mother, Mari, discovers that she made a panicky 911 call before leaving her “John” -- and that police took more than an hour to arrive.

Based on a bestseller by investigative journalist Robert Kolker, this movie’s propulsive storyline serves as a scathing indictment of police, who seem almost wholly unresponsive to the missing-persons case -- even to the point of never asking for video-surveillance footage from the head-honcho of the gated community where Shannan vanished. And he turns out to be a prime suspect!

Things get hotter when a local beat cop, stopping near the scene just to let his dog out, happens upon four long-buried corpses -- none of whom is Shannan. But they were all Craigslist sex workers, and this fact seems partly to fuel the horrific apathy that keeps Mari from making any progress in her search.

Ryan’s fierce mama-bear simply will not be denied; yet she is no hero, seemingly ignoring her two younger daughters as she drags them with her through every step of the investigation. Those redoubtable young ladies are beautifully played by Thomasin McKenzie (“Jojo Rabbit,” “Leave No Trace”) and Oona Laurence (“Southpaw,” “Pete’s Dragon”); if you’re a film-fan, you probably already have your eye on these two up-and-coming actresses.

Mari also gets quite a bit of help from female friends and family of the other victims, with standout work from Miriam Shor and Lola Kirke as two of those stalwarts.

Considering the authentic nature of its events, “Lost Girls” remains truly hair-raising in a couple of spots, especially as Mari threatens to get in over her head with the aforementioned suspect -- a local doctor who is intensely hard to read, but nonetheless scary.

The film is topped off by excellent photography and music. But whatever you do, don’t skip the updates that appear just before the closing credits. These put potent punctuation on the movie’s storyline; the whole thing is a testament to what happens when those in authority ignore the disenfranchised -- and a bracing tribute to one mother’s relentless determination.

“Lost Girls,”

directed by Liz Garbus

Run time: 95 min.

Rated R for strong language