Francis Alÿs

No-one ducks or runs for cover when Francis Alys leaves a gun shop carrying a pistol and walks with it through the streets of Mexico City. Someone calls the cops, though, because, about 12 minutes into the Belgian artist's film 'Re-enactments' (2000), up rolls a police car and the artist is duly carted off. It's a confounding scene. Is the film about endemic violence in the artist's home town? Is it even for real? Showing on an adjacent screen is footage of the same event filmed from different angles at a different time. Apparently (and conjecture figures strongly in Alys's work) the artist persuaded the police to replay the incident for his camera.

In fact, the idea behind the piece was to draw attention to the chasm between live art and its edited documentation. This, then, is a work that undermines its own veracity, a clever/stupid stunt that seems perfectly in tune with the title of this retrospective, 'A Story of Deception'. More often, Alys's art is delivered with a clearer sense of allegory. In 'The Green Line' (2004) we see the artist, carrying a leaking can of green paint, traipse the route of the armistice boundary through Jerusalem which was drawn on a map in green pencil by Moshe Dayan after the 1948 Arab-Israeli war.

In revealing the rules that bind us and the lines that divide us, Alys comes across as a mixture of poet and politician, part prankster, part messianic figure. For the 2002 film 'When Faith Moves Mountains', he enlisted 500 volunteers to shift sand on the outskirts of Lima, their Sisyphean effort - motto: 'maximum effort, minimum result' - an inversion of the guiding principles of economic efficiency. Not a bad day's work for an in-demand Western artist, you might think, but Alys reserves some of his most futile actions for himself: like pushing a block of ice around hot streets until it disappears into a dirty stain ('Sometimes Doing Something Leads to Nothing'), or herding sheep around the flagpole of Mexico City's main square until it becomes difficult to discern who is being led by whom ('Patriotic Tales').

Often, an embrace of failure underpins these absurd actions but Alÿs is so brimful of ideas, any one of which might sustain a lesser artist, that he instils a sense of hope. His energy, along with his optimism, pulses through this funny, touching, beautifully-paced show.