A Real Pain is a sublime, Rolls-Royce version of that often mis-handled genre: the mismatched-buddy comedy. Jesse Eisenberg’s second film as writer-director (after When You Finish Saving The World) pitches two Jewish cousins on a journey to honour their family ancestry in Poland. The result is a by turns funny, solemn and emotional road trip that flies by on two superb central performances from Eisenberg and Kieran Culkin.

Eisenberg economically sketches his diametrically opposed protagonists. His David is strait-laced and slightly nervy, living a successful life selling digital ad space in New York with a wife (Ellora Torchia) and adorable son (played by Eisenberg’s real-life son Banner). Culkin’s Benji is a loud-mouthed loose cannon, a wastrel who is going nowhere — he airmails weed to his hotel in Poland — but has enough charisma to get himself out of any situation.

Hooking up with their Holocaust tour group — perky...