It’s been said that life is what happens when you’re busy making other plans, and such is the story of partners Sam (Colin Firth) and Tusker (Stanley Tucci). The two men are taking a road trip through the English countryside, visiting friends, family, and special places from their past. The two reminisce on their decades-old relationship, and things seem to be going well — until one day, Sam finds Tusker standing in the middle of traffic, confused about where he is. Do not dismiss “Supernova” as just another movie about dementia, which seems to be the topic du jour of late. Writer / directo...