Ella (Mirren) and John (Sutherland) just up and leave one morning without even telling worried children Will (McKay) and Jane (Moloney), who are already at the end of their tether with them. With John struggling with dementia and Ella suffering from cancer the couple figure this is their last chance to visit Hemmingway’s house in Key West and so they start up their ancient Winnebago and head south…

Despite numerous scenarios where Sutherland, a former English professor, waxes lyrical about his favourite writer, boring and delighting waitresses in equal measure along the route, the story can’t quite sell the Hemmingway house as being all that big a destination to reach. It’s never a desperate need for the characters and the couple could turn back at any point. Low stakes and an underpowered narrative this could have been but of course with road movies it’s never the destination but the journey and these two characters certainly experience an emotional one.

Director Paulo Virzi, who delivered the rather heavy 2013 Italian drama Human Capital, takes an easy going approach to this touching comedy drama; adapted from Michael Zadoorian’s novel the story lives and dies with its leads, revelling in the random conversations motormouth Mirren and silent Sutherland enjoy. The two present a real life lived, both still raw from past indiscretions and both enjoy the kind of shorthand long-term couples have. They look after each other – he reminds her about her medication, she does what she can to help him remember their family. It’s the latter that dominates as Sutherland’s mind slips slowly away the closer they reach the Keys.

The film finds joy in the small things: nice parks, ice cream, pictures of children, and a good burger, a stop and smell the roses story that’s sad and funny and lovely and sad, switching back and forth without every losing its overall relaxed vibe. “I love it when you return to me,” Mirren tells Sutherland in one of his rare moments of clarity and her face is wonderful as it falls when she realises he’s losing himself to confusion again. And yet it’s not all sweetness and sunshine with Sutherland making Mirren promise to put a shotgun in his mouth and remind him why he’s doing this before walking away.

Mirren and Sutherland are wonderful as the aging couple who have yet to learn things about life, even at this late stage. Sure it can be corny and safe but the ending is wholly unpredictable. Chalk this one up as a surprise.