We are running out of time.

There are only a few filmmakers who have had a creative run as astonishing as Francis Ford Coppola's four-film string of masterpieces in the 1970s. Given that his subsequent output has been at best uneven and at worst a staggering fall from greatness, it makes sense that the 70-year-old director, vintner and raconteur would be preoccupied with the theme of returning to one's youth to change the present. It's a theme that was used for light humor in Peggy Sue Got Married, for baroque romance in Dracula, and to physically hurt the audience with Jack. In Youth Without Youth, Coppola's most intimate film since the critically panned (and ripe for rediscovery) One From the Heart, the idea of starting over and finishing old business is at the heart of a sprawling discourse on philosophical, metaphysical and esoteric notions that have presumably been on Coppola's mind this past decade. As a film it's alternately compelling and confounding, but as an extension of Coppola's towering persona - at once visionary, pompous, epic, kitschy and nakedly personal - it's fascinating.

Opening in 1938, Coppola's film finds as his surrogate a 70-year-old linguistics professor, Dominic Matei (Tim Roth), whose plans to end his own life are interrupted by a bolt of lightning (an unintentionally hilarious moment). As he recovers in a local hospital, Dominic is informed by his doctor (Bruno Ganz) that he is undergoing a remarkable physical transformation - while his mind still contains the memories and knowledge of an elderly man, his body has rejuvinated itself, transporting him to the physical state of his youth. It's a concept that Coppola has a good deal of fun with in its early stages, turning Dominic into a kind of egghead superhero who uses his supernatural cognitive powers to evade Third Reich scientists eager to exploit his mysterious abilities while also using his rediscovered libido to bed a Nazi spy (Alexandra Pirici) - it's fantastically pulpy stuff, and Coppola's fearless enthusiasm is infectious.

The narrative grows more complicated as time progresses and Dominic encounters Veronica, a similarly gifted young woman (Alexandra Maria Lara) who reminds of his long-lost love and is given the opportunity to finish his life's work, the discovery of a "proto-language" Dominic believes will return humanity to some essential form. Adapted from a novella by religious historian Mircea Eliade, this is heady literary material for a film, and it's a pleasure to watch the director mirror his protagonist in a story that weaves between genres and forms and touches upon philosophy, theology and mythmaking with the wide-eyed enthusiam of a 20-year-old liberal arts student. The filmmaker's uncanny sense of rhythm and the employment of recurring symbols (roses, in this case) remind of his once-unparalleled grasp of such filmic flourishes. If Coppola's goal was to start over than he's succeeded - the film has the stylistic abandom of a first-time director - and yet it's his maturity, his willingness to embrace his film's hermetic interior world, that leaves a lasting impression.

While the ideas on display here are worthy of discussion, they don't always translate effectively to cinema. The ongoing dialogue between Dominic and his double (also Roth), composed of matching shots of the actor and canted angles, reminds too strongly of Gollum to work and quickly grows irritating. And while Coppola's earnestness is admirable, it sometimes leads to unfortunate guffaws, as when Dominic matter-of-factly informs Veronica "that stranger in your dream was probably Shiva." The conflict that drives the final part of the film - whether Dominic should complete his work at the expense of Veronica's life or choose love - is interesting conceptually but lacks dramatic impact. Most of this is probably attributable to Coppola's long absence from filmmaking; I can't wait to see his next film to find out if he's gotten the lead out.

The sweetest and most enduring thing about Youth Without Youth is how it works as a return to forgotten cinematic languages. Shot in hi-def, the film nevertheless begins with old-fashioned title cards and journeys through noir, sci-fi and romantic scenes all filtered through a nostalgic haze. In paying homage to the movies of his youth, Coppola succeeds in making his film a tribute to the childlike wonder of cinemagoing - the idea of film-as-magic-show he's returned to over the years - that reminds that Coppola is perhaps cinema's greatest living romanticist. The clunkier aspects of Youth Without Youth are made forgivable by its willingness to fail in search of a cinematic proto-language, an aim at once grandiose and humble. More than anything, Youth Without Youth lingers in the mind as the work of a once-lost cinematic master who has found his voice again, and (hopefully) the promise of more masterpieces to come.