When the French give the world an international pop star, which isn't all that often, they tend to be unforgettable — Edith Piaf, Maurice Chevalier, and, maybe most unusual of all, Serge Gainsbourg. A new and unconventional feature film about him, called Gainsbourg: A Heroic Life and starring Eric Elmosnino in the title role, opens at the Esquire Theatre in Clifton tomorrow. After the 1:10 p.m. Sunday screening, local arts writer and CityBeat contributing editor Steven Rosen will lead a discussion about the film and about Gainsbourg's impact and life in general. For more information, visit www.esquiretheatre.com. Check out the film's trailer below.