It’s not every movie that gets to capture a real-life miracle unfolding right in front of its cameras, but that’s exactly what happens in Robin Berghaus’s sensitive and unassumingly astonishing documentary "Stumped," Thursday night’s opening selection for the 2017 Milwaukee Film Festival.

Like a feel-good Frankenstein story, the audience watches as death becomes life, limbs slowly moving again where there weren’t even limbs before in a weird and wondrous tribute to the power of science, the human body and the human spirit. It’s a modestly jaw-dropping moment whose emotion and awe sneaks up on the audience – even walking in knowing the story.

Maybe an even bigger miracle, though? The rest of "Stumped" is just as good, living up to the marvel of modern medicine at its core by focusing on the reality of its subject’s unreal situation.

It’s a story that the creators of "House" are likely kicking themselves for not writing: Will Lautzenheiser, two days into teaching his first film classes at Montana State University, comes down with what seems to be just a painful pulled muscle. Over time, however, his ailment grows into something much worse: a freak bacterial infection that invades his body, forcing doctors to amputate all of his limbs to save his life. After years of coping, adapting and rehabbing into his new state – with the devoted help of his partner, Angel – a new option arises: a double arm transplant, a risky and experimental procedure with a hefty list of dangerous side effects and no guarantee that he wouldn’t be left still handicapped, if not even more so. But if it were to succeed, he’d have part of his former life and former independence back.

Oh, and in the midst of all of that medical drama, Lautzenheiser also launches a small career in stand-up comedy, turning his hurt into humor at a small Boston improv comedy club. And while he may not have arms or legs, he’s head and shoulders above most open mic night performers.

Making her feature film debut, Berghaus leaves most of the bold experimenting to the doctors, leaning fairly conventional with her direction and visual approach with the typical mix of interviews and no frills cinema verite day-in-the-life footage (a rare, moving exception: a GoPro-aided sequence following Will’s challenging new shower routine, interwoven with old footage of him playing as a carefree child).

But while there’s little unexpected there, Berghaus’s approach to Will’s story is full of pleasant surprises, avoiding the Upworthy route of going for easy uplift and treacly inspiration. An interview between Will and his brother Tom early on in the story even features some quick close-ups of some cards saying "Get well soon" and a cutesy quote about how exhausting it is to be normal, and you can almost hear the camera rolling its eyes at the trite, fake feel-good they’re peddling. Another intimate chat notes that people in Will’s condition are often viewed as just one of two things: figures of pity or figures of inspiration.

"Stumped" chooses a third option: a person. So instead of a simple, mawkish heartwarming story, Berghaus really goes into the human nuances of Will’s struggle: the loss of independence his condition forced upon him, the exhausting rehab process and difficulty in learning how to walk with a whole new center of gravity, the grave side effects of his surgery even if successful (the aminosuppressants required afterward can lead to cancer or diabetes, making even his cure a potential killer).

And it’s not entirely his struggle. There’s obvious but mostly unspoken stress between Will and Angel about the sharp detour their lives have taken as individuals. A sequence between the two making pizza shows it all, the tension and the tenderness that feels all too real between people who love each other but can’t love their new circumstances.

As you'd hope for from a movie about a stand-up comic, there's good humor too mixed in with the hardships. Will makes for a great subject, not just because of his incredible story but because he’s an incredible character with a surprisingly grim but playfully self-aware and candid sense of humor. His stand-up abilities are indeed no joke, and I imagine many will dive to YouTube to find his "My Life As A Cat" videos oh-too-briefly glimpsed. Berghaus allows Will and everyone around him to be fully fleshed out characters, people you quickly grow to care for within the doc’s brisk 72-minute running time.

That human grounding, how real Will’s struggles and successes are depicted, makes the moments of inspiration in "Stumped" feel all the more rewarding. When it becomes time for the surgery, while by no means flashy, it’s a burst of startling intensity (the surgery requires precise timing and connections for both arms – within a short time limit too). It helps that the science is inherently fascinating too, both Will’s case as well as Berghaus’s quick sprint through the engrossing and sometimes controversial history of organ donation.

Fitting for the movie, it’s the smaller moments that make the biggest emotional hits, like Will’s comedy partner thinking about the importance of goosebumps or Will’s quietly selfless reasoning for accepting this potentially dangerous procedure. It seems all too right that the biggest cry moment in "Stumped" belongs not to some big gesture or even the surgery's results, but to the unseen parents of the donor’s arms and the brief statement they make to Will after his surgery.

Even afterwards, "Stumped" doesn’t allow for an easy end – because there is no easy end. The film still has about 15 minutes left after the arms are attached, which is mostly spent watching Will go through more painstaking rehab, his arms slowly gaining feeling and strength but still mostly limp and directionless, his brain having to relearn what most take for granted. One fellow arm recipient talks about the immense importance of merely being able to brush aside one’s hair. It’s an inspirational journey because it is a journey – one still in progress.

But with a sweet flick of a light switch at the end of the credits, Berghaus finds the perfect, slight grace note to conclude this sweet if incomplete human miracle – and make "Stumped" a bit of a miracle in its own right.

"Stumped": ***1/2 out of ****