Helen Mirren and Donald Sutherland as road-tripping senior spouses thumbing their noses at mortality — what could go wrong? A fair amount, it turns out, in this thin comedy from Italian director Paolo Virzì (“Human Capital”). John (Sutherland) is suffering from Alzheimer’s, though his dementia comes and goes with a convenience that suits the plot. His wife, Ella (Mirren), has decided they’ll take their old RV down the East Coast to the Ernest Hemingway Home in Key West, Fla., as the author is a favorite of her retired-professor husband.
Ella’s a gregarious type who rattles on at everyone they meet with a lonely desperation, which becomes understandable (if no less tiresome) when she’s alone with John: He frequently forgets who she is and where...