Producers: Emily Morgan and Tristan Goligher   Director: Harry Macqueen   Screenplay: Harry Macqueen   Cast: Colin Firth, Stanley Tucci, Pippa Haywood, Lori Campbell, James Dreyfus, Ian Drysdale, Peter MacQueen and Nina Martin   Distributor: Bleecker Street

Grade: B

Harry Macqueen’s film is a poignant tale of a couple facing the heartbreaking effect of encroaching mental deterioration on their long and loving relationship.  It’s comparable in some respects to Sarah Polley’s “Away from Her,” Richard Glatzer and Wash Westmoreland’s “Still Alice” and Elizabeth Chomko’s “What They Had,” except that in this case the partners are gay.

“Supernova” is also a road movie, in which Sam (Colin Firth) and Tusker (Stanley Tucci) barrel along the highways of northern England in an R.V. en route to a concert where Sam, a pianist, is to take to the stage again after a hiatus caring for his lover. Tusker, a novelist, is suffering from early-onset dementia, and the condition leaves him open to forgetfulness, an inability to write, and a realization that his very sense of self is gradually disappearing. 

Tusker is also an amateur astronomer, and the screenplay uses that avocation to put forward a metaphor comparing his condition to that of a dying star—a phenomenon depicted in an opening shot of the night sky.  Later Macqueen builds on the analogy when he has Tusker discusses stars with Sam’s niece and goddaughter Charlotte (Nina Marlin).

The occasion for that conversation is one of the stops along the way, a visit with Sam’s sister Lilly (Pippa Haywood) and her husband Clive (Peter MacQueen).  During the stay their hosts throw a birthday party for Sam, with a bevy of old friends in attendance.  But even here the tone is bittersweet, since the failing Tusker must ask Sam to read the congratulatory message he’d written for the occasion since he’s no longer capable of doing so himself.

That’s only one instance in which the trip takes on an emotionally complicated feel.  A stop at a diner includes a playful exchange with a waitress, for instance, but it’s quickly followed by a scene in which a panicky Sam searches for Tusker, who’s wandered off with their dog Ruby.  A similarly mixed air of affection and sadness suffuses a sequence in which the two men camp at the lake where they first met, intermingling nostalgia over the past with quiet despair about the future.

All such moments, as well as the astronomical metaphor, have a degree of obviousness about them—like the other films mentioned above, “Supernova” can’t escape a whiff of a disease-of-the-week tearjerker. Nor will the revelation of what Tusker has in mind come as much or a surprise to anyone (it certainly doesn’t to Sam).

Yet the film escapes the mawkishness that can afflict such stories—as did the others noted above—through the excellence of Macqueen’s writing, which captures the give-and-take bickering between the two men, as well as the depths of sorrow that mark their more serious conversations, and the quality of the lead performances.  Firth and Tucci are good enough to persuade us that Sam and Tusker have actually been together for so long and understand one another so completely that they can practically read each other’s thoughts and automatically respond to the other man’s needs.  And while the film is genteel about showing the sexual side of their relationship, it conveys their intimacy. 

Visually the film is fastidious, with Sarah Finlay’s production design impeccable, even in the R.V. interior, and complemented by rich cinematography by Dick Pope that offers images of the region the couple travels through that are often as stunning as paintings. Chris Wyatt’s unhurried editing adds to the mood of quiet melancholy, as also does Keaton Henson’s score, although the piano compositions, one of which takes pride of place at the close, aspire to depth rather than achieving it. 

The story that “Supernova” tells may not be an unfamiliar one, but it rarely strikes a false note, and is elevated by superior acting.