“Trunk: Locked-in” is a tense and paranoid “work the problem” thriller about a woman struggling to get out of the Audi trunk she’s been drugged and stuffed into, desperately reaching out via cell phone for help from family, the authorities — anybody.

German writer/director Marc Schießer’s debut feature never goes far wrong as it drowns us in claustrophia, doling out tiny clues about our victim, what happened to her and possible reasons for it. And it’s never off-base trapped in that trunk with Malina, given a smart, urgent, mind-racing edge by Sina Martens in the film’s best moments.

The thriller’s energy flags as this rational victim stops reasoning, pleading and suffering through her plight long enough to make us despair that she’ll ever “get it” and get back on task. And the claustrophobic Malina’s-point-of-view-only bond is broken by the filmmaker in the third act of this real time “ticking clock” thriller. But it’s still a genuine German-language (with some English) nail-biter.

She wakes up in the half-closed trunk of a late model Audi, parked in an alley in the rain. Malina finds out she can’t move her legs to escape. But she grasps at the garbage bag — one of several — lit-up by her ringing phone, which is stuffed in it. Her unseen tormentor closes the trunk on her as she plays dead and he finishes disposing of those bags.

She’s been “taken.” What will she do? How can she escape?

Schießer’s camera is stuffed into that trunk with her as she starts to seek clues and give us others. She methodically takes account of her physical state — legs, “up to the spinal cord” — like a doctor or ER nurse.

She’ll find a gaping wound, eventually.

Malina turns on the cell flashlight and pokes around for release mechanisms and tries to push open the trunk. She takes inventory. There isn’t much here but her phone and her boyfriend’s small GoPro style camcorder. That’s how she sees the kidnapping and gets a glimpse of her captor.

Yes, that’s cheating.

Malina’s sister calls and a frantic Malina cannot convince the self-absorbed chatterbox that this isn’t more of her “drama.” Sis snarkily sends a “How to get out of a locked trunk” tutorial.

Her father flips out and is sure it’s someone who has a grudge against him or their family. He won’t call the police.

Only emergency operator Elisa (the voice of Luise Helm) takes Malina seriously and seems up to helping her. Eventually.

“Are you under the influence of drugs right now?”

Schießer sticks us in that trunk with Malina, doing the same inventory she does, following a few of the tutorial’s tips, as the movies have taught us to do, and often wishing there was just a tad more room in there for us to grab Malina. One feels the need, on many occasions, to give this 27 year-old a good SHAKING when she loses the plot, takes time to watch old videos of her and her boyfriend as her phone battery dies and she lets the ticking wind down towards some 4:30 meeting where she’s overheard her fate will be decided.

But her skill set is believable, her pain tolerance admirable and her reasoning — when she applies it – impressive. I love “work the problem” stories, and Schießer rarely cheats his way into melodrama. When he does, the picture loses its mojo.

Martens — she was in a German Netflix thriller, “The Perfumier” — makes a compelling heroine, appreciated for her enterprise and toughness, feared-for thanks to her easily-grasped vulnerabilities. As many “reasons” as the script has for putting Malina in this “Trunk,” the viewer knows most of the answers before Malina does.

The cleverest thing is how we have no idea if she’ll make her escape, and just what she’ll go through in the many ways that she’ll try.

Rating: unrated, violence, profanity

Cast: Sina Martens, Poal Cairo, Artjom Gilz, with the voices of Luise Helm,
Janina Sachau and Charles Rettinghaus

Credits: Scripted and directed by Marc Schießer. An MGM/Amazon (Jan. 26) release.

Running time: 1:36