Sorry to invoke Morrissey, but in the pantheon of lovesick declarations, his ballad of mutually assured destruction might be up there with the greats. "To die by your side is such a heavenly way to die": a line immediately inducted into the softboy hall of fame, and also taken a little too literally, perhaps, by Katia and Maurice Krafft – the French volcanologist couple who lived, worked and, yes, perished side by side in a spectacular eruption in 1991.
The doomed husband-and-wife duo are the subjects of Fire of Love, a documentary that won an editing prize at this year's Sundance. It's not difficult to see why: in the hands of director Sara Dosa, it flits seamlessly between archival footage of the Kraffts's many expeditions, fairytale illustrations, and stylised re-enactments of memories preserved in the pair's sprawling diaries.
It is functionally a biography of two scientists – but also a grand treatise on the seismic thrill of romance, enough to thaw out even the most hardened cynics.
The Kraffts, over their three-decade career, cut a striking image as they clamber up craggy cliff faces and across perilous passages between lakes of lava threatening to swallow them whole. In beet-red beanies and turquoise wind-breakers (it may as well be called The Life Volcanic), they possess a crazed – and often wryly hilarious – disregard for their own survival.
More than once, blistering, molten ammunition arcs through the air around them as they potter nonchalantly beneath, as if taking a sunny stroll through a park.
Most times, barely a layer of fabric separates them from a smouldering demise. When they do – briefly – trial protective gear, it's a flimsy sheet of metal engulfing their entire heads, resembling, more than anything, a costume-store Ned Kelly.
All this in pursuit of their other love: the volcano.
We know, from the outset, how their story will end: engulfed by a pyroclastic flow when Japan's Mt Unzen suddenly erupts on a research trip. There is video of Katia's last moments, sprinting away from a rapidly mushrooming gas cloud – haunting in the way all disaster footage can be, as an uncomfortable glimpse into mortality.
Yet this outcome, rather than casting a melancholy shadow over the rest of the film, imbues it with a sense of peace.
Indeed, Fire of Love sometimes plays like a long, loving elegy.
The Kraffts's lifelong fixation, we are told, begins in adolescence, both of them independently awe-struck by the majestic unpredictability of volcanoes. They meet by chance in 1966 – a meet-cute to rival any rom-com, depicted in a recreation that recalls the twee sensibilities of Wes Anderson or (500) Days of Summer.
There is no definitive record of the encounter, but varying versions show cups of coffee left unfinished, park benches flanked by swaying trees, and split screens of Katia and Maurice appearing to gaze into each other's eyes. With a wink, it skirts the line between charming and cloying.
So does the narration, courtesy of filmmaker and writer Miranda July (Kajillionaire; Me and You and Everyone We Know). With her classic honeyed lilt, July unwinds the Kraffts's tale like a bedtime story.
The couple's romantic relationship soon blooms into a working one. Before long, they are venturing to far-flung volcanoes in Iceland and the Democratic Republic of Congo to study their rhythms, reporting their findings to an immediately idolising public via news and talk show appearances.
Katia is the geochemist; Maurice the geologist. The difference is hardly a few syllables, though Fire of Love paints them as yin and yang.
She is a bird, Dosa suggests – careful, precise, and detailed. Meanwhile, he is an elephant seal, with a voracious appetite for documentation.
It's Maurice's cinematography, shot on vibrant 16mm, that comprises much of the film – years of labour culled to a tight 90 minutes.
By the end of their lives, the Kraffts had collected some of volcanology's most groundbreaking observations, and contributed to warning systems that would save thousands from deadly eruptions – though you wouldn't be able to tell based on Maurice's footage alone.
The sheer goofiness of that footage works to offset what could easily become self-indulgent. Unlike other portraits of extreme thrillseekers – Oscar winner Free Solo (2018), say – Fire of Love never mines for cheap spectacle.
Instead, there's a lived-in ease to the whole affair. The camera follows Katia making googly eyes as intensely as it watches a volcanic explosion.
In an astounding interlude, it descends into zany comedy as the Kraffts and their compadres ride off into the mountains on horseback, the stars of their own kitschy western.
Sometimes, Fire of Love can skew slightly too saccharine. "Across humanity's two million years, two tiny humans are born in the same place, at the same time, and they love the same thing," July intones, giving misplaced weight to cosmic fate in a documentary that has otherwise focused on a more earthly kind of grandeur.
When it works, though, the narration can evoke the same wide-eyed giddiness present in much of July's own oeuvre, which brims with unorthodox heroines breaking away from restrictive arrangements to discover the world in weird and fantastical fashion.
It's easy to imagine Katia and Maurice slotting into one of July's films, as idiosyncratic and headstrong as they are. They, too, are fleeing from reality, their quest spurred by a "disappointment with humanity", as Maurice admits.
But up on a trembling mountain, that disappointment gives way to an all-consuming love – for each other as much as for the mesmeric volatility of nature.
"What is it," July questions at one point over a Brian Eno cut, "that makes the Earth's heart beat? Its blood flow?" Suddenly, a whisper of synths snowballs into a glimmering outburst; we cut to a pair of silhouettes dancing beneath a firestorm.
As cheesy as it sounds, we, too, might begin to understand the Kraffts's obsession, taking solace in our own relative insignificance – our lives merely a speck of ash on a gargantuan, indifferent rock.
Fire of Love is in cinemas now.
