We have all seen photographs by Weegee of mid-20th-century New York, the crowd on Coney Island beach, the dead gangsters outside the Italian restaurants, the summer hydrant showers. But this huge retrospective, the fullest there has even been in Britain, is something else. Pictures you may have loved or just been aware of as part of New York's atmosphere, become hallucinatory, to the extent of raising a question about their authorship. It's not that the identity of the man who pointed the camera, born Usher Fellig in Poland in 1899, is in doubt. The question is who or what is working through him.

There's shot after shot of people gunned down, decapitated, drowned or burned. The decapitation photograph is terrifying as you slowly recognise the cabbage-like object in the street. It's not just the efficiency of Weegee as a photojournalist that makes these pictures uncanny but the way the people of New York share their dreams and terrors with his camera.

The power of Weegee's photographs is in their oscillation between drama and mundaneness not just from image to image - but in the texture of each shot. That's why it's great to see the original, crinkled, oily prints rather than reproductions. The iconography of his photographs is that of 40s and 50s film noir, yet Weegee's streets are grimier, cracked, littered; in one two-shot sequence he even captures a street's destruction by gas explosion. You feel you are seeing not the myth of New York but the truth, which trumps the myth by miles.

There seems to be some unconscious connection between Weegee and the collective life of Manhattan. The way people look at him in that Coney Island beach photograph, waving, sitting on each other's shoulders, probably shouting a few obscenities, gives tangible form to the idea of a "community". With all the violence and horror, it's this that shines out of Weegee's photographs. When he captures an Easter promenade in Harlem, or children dancing in a hydrant shower on a July day, you envy these people their passionate common life. Even in the pictures of murders people stare together at a corpse, weeping, laughing, or just gawping.

Weegee has himself photographed alone at the wheel of his car, cruising the city like Travis Bickle in Taxi Driver. But unlike Scorsese's anti-hero of urban alienation, Weegee makes a connection with the people he meets in the night. I Cried When I Took This Picture, he titles a shot of witnesses at a fire weeping for relatives and friends, and you know he did.

Until July 2. Details: 01865 722733. ***** Unmissable **** Recommended *** Enjoyable ** Mediocre * Terrible