As you watch Supernova—writer/director Harry Macqueen's light-on-dialogue, heavy-on-emotion tale of a gay couple coming to terms with the fact that one of them is experiencing early-onset dementia—you keep getting struck by the amount of trust the film places in its two leads.
Which makes sense, considering that the two leads in question are Colin Firth, as British concert pianist Sam, and Stanley Tucci, as American novelist Tusker. The latter is the one who is losing himself, and who seems, of the two of them, much more sanguine about it.
In an early, wordless scene, Tusker wanders away from the RV in which the two are touring the British Lake District. A worried Sam drives along a narrow country lane until he spots Tusker; as he gets out to retrieve him, Macqueen's camera stays in the RV, looking out at the two of them through the windshield. Sam approaches Tusker, and reassures a concerned motorist that everything's fine. (Everything is not fine). Tusker sees Sam and breaks down; they embrace.
A lesser film would place us up with them, in the middle of that embrace, amid the tears and relief and whispered assurances. But Macqueen—an actor himself, and a good one, a fact which seems not inconsequential here—knows we don't need it. Tucci and Firth can sell that moment, in all its panicked intimacy, just through the set of their shoulders and the way their bodies slump into one another.
Supernova is marked by that kind of knowing restraint, that delineates the difference between sentiment (true, earned emotion) and sentimentality (the cheap, manipulative attempt to tug at our heartstrings). In scene after scene, as the two men visit friends and family one last time, we glimpse the showier, more maudlin film that Supernova could but never does devolve into, hovering just at the edges. Only in its closing moments, which are predicated by a dramatic conflict of the sort that stories like this one require, does the movie become the "here's one for the Oscar reel" actorly showcase it's always threatened to be, but the track has been carefully laid, and its hard to begrudge these two actors the chance to dig in.