Dir: Wolfgang Becker. Germany. 2003. 123mins.

Leading a strong home team at this year's Berlinale, competition entry Goodbye Lenin! is a high-concept fall-of-the-Wall comedy drama that has much going for it: a strong script, an extremely watchable lead in Daniel Bruhl, photography with a sharp, clean, cinematic gloss and a Nyman-like soundtrack by Amelie composer Yann Tiersen. It is over-indulgently long at just over two hours, but this will not prevent it from being that rarest of quantities, a successful German film export. A healthy performance will be spurred on by the nature of the material and the striking marketing campaign designs, which draw on the great tradition of Soviet avant-garde film posters. Indeed, it is all so cleverly done and likeable, that even the US, a notoriously difficult market for German films, is likely to embrace Goodbye Lenin! Either that or remake it, featuring a Cuban hard-liner who falls into a coma and is smuggled over to Miami.

The idea is simple, and potentially dumb: a dedicated East Berlin socialist (Katrin Sass) falls into a coma just before the fall of the Wall in November 1989, and snaps out of it several months later. But her health is still so fragile that her son Alex (Bruhl, a sort of German Ewan McGregor) decides to spare mum a potentially fatal shock by pretending that nothing has changed.

He is able to do so because she is bed-ridden, and her room at home becomes a shrine to a fast-disappearing world, with its hideously unstylish synthetic clothes and fabrics, flimsy plywood furniture and Young Pioneer singalongs. Much of the humour is generated by the son's increasingly desperate attempts to shield his mother from the truth: these range from the decanting of groceries into their original Communist-era jars and bottles, to the production - with the help of a wannabe filmmaker friend - of fake East German TV news programmes that are relayed by video from the next room.

But Goodbye Lenin! turns its sitcom premise into something a little more profound. It does this by developing the mother-son relationship emotionally, making it more than just a peg for some hilarious gags. But it also suggests that there is a political and moral truth behind the fantasy world, the utopian German Democratic Republic, that the son so heroically and painstakingly constructs in order to account for the increasingly unavoidable events that are going on just outside the window.

Bernd Lichtenberg's script, which picked up a German screenwriting award in 2002, is admirable in all except for its length. It's a textbook example not only of how to use subplots (like that of the father who fled to the West years before) and supporting roles (like Alex's sister, who gets a job in Burger King, or his Russian girlfriend) to advance the story and flesh out characters and motives, but also of how to turn the whole genre of a film around.

By the end - when a fine climactic scene, underlined by a swelling orchestral crescendo, provides the key to the film's title - what might have been a single-track comedy has become a moving, multi-layered drama.

Prod co: X Filme Creative Pool
Co-prod: WDR/arte
Int'l sales: Bavaria Film International
Prod: Stefan Arndt
Scr: Bernd Lichtenberg
Cinematography: Martin Kukula
Prod des: Lothar Holler
Ed: Peter R Adam
Music: Yann Tiersen
Main cast: Daniel Bruhl, Katrin Sass, Chulpan Khamatova, Maria Simon, Florian Lukas, Alexander Beyer