At the beginning of "Supernova," the screen is black for a long time, long enough that you may start to think there's something wrong.

The darkness is meant to be disorienting, an early sign of the confusion to come in a movie about who must decide how things go when someone has dementia: The person who is sick, who's obviously the most affected? Loved ones, who may see the big picture better?

Stanley Tucci plays a writer with dementia, and I'm sorry to report that his character is called Tusker and that a name better suited to a resident of a zoo is going to appear frequently in this review. He and husband Sam (Colin Firth) open "Supernova" in a recreational vehicle, debating next steps for Tusker and driving to visit family. (Bet you never thought you'd see Firth, the best Mr. Darcy, in the same sentence as an RV.)

"Supernova" is a deliberate, rhythm-of-life kind of movie, one that takes its time with mood and character (the leads' pattern of playful bickering feels especially real). Once it gets going, though, it explores interesting things I don't think I've seen in a movie about dementia. Tusker, it develops, is further along than Sam in terms of accepting his illness, and Sam's unwillingness to face facts is harming both their relationship and their ability to make some big choices.

Writer/director Harry Macqueen's script gets sentimental toward the end, allowing difficult issues to be resolved too tidily, but along the way it pauses to share surprising insights into the characters.

"You know what the hard part is? You're not supposed to mourn someone while they're alive," Tusker confides to his sister-in-law, who reassures him, as one would, "You're still you." A hokier movie might leave it there, but "Supernova" has Tusker reply, "No. I'm not. I just look like I am." Then, it caps off that devastating line with a rueful joke as Tusker takes a look up and down his body and adds, " ... which is a shame."

That joke is slightly disingenuous, since there's a sizable gay audience that is eager to see "Supernova" not because it's about a couple grappling with dementia but because Tucci is hot and shirtless in it. But Tucci's gentle performance tells us a lot about Tusker, who is grateful for a good life and resolute about his future, even if his loved ones are not on the same page. (That the couple are gay is barely a factor in "Supernova," which feels right, given everything else at stake.)

If it seems like I'm writing around some elements of "Supernova," that's because I am. Hot-button issues are introduced fairly late in the game, and Macqueen does not handle them with the delicacy or care he devotes to the first two-thirds of the movie. Everything happens too quickly because Macqueen imposes an artificial deadline on Tusker's and Sam's decisionmaking that seems to have more to do with "Supernova" running out of time than Tusker.

In the end, though, Macqueen allows us to spend enough time with the men that, regardless of whether we agree with their decisions, we do understand where they came from.

Chris Hewitt • 612-673-4367


⋆⋆⋆ out of four stars

Rating: R for language.

Theater: Wide release and streaming Feb. 16.