Arshile Gorky

The Armenian-born artist famed for his hand in shaping abstract expressionism, America's most explosive painterly movement, was more of a follower than a leader. Perhaps evading the immigrant's lot of lonely exile and cultural marginalisation, this impostor to the throne of pre-war abstraction switched identities and styles like hats, until a genuine late flowering in his talent was cut short by a crippling car crash and his suicide in 1948.

This chameleon-like existence began after he quit his troubled homeland in 1920, having witnessed Ottoman Turks lay waste to a whole generation of Armenians, including his mother, who he watched die of starvation. Arriving in New York, he changed his name (from Vosdanig Adoian to the revolutionary-sounding Arshile Gorky) and invented an impressive CV of European exploits. He slavishly mimicked Cézanne and Picasso before settling on his own style of biomorphic abstraction, itself derivative of Miró, Kandisnky and Arp.

If such a tormented early life sounds like substantive grist to an artist's mill, spare a though for the poor viewer who has to suffer his long-fought wranglings with memory, throughout this tiring show of more than 150 pieces. Like Gorky's slippery identity, his spiky, vaginal and ocular shapes with their crude black outlines resist easy appreciation, sliding off the canvas as soon as they form. But the path to painterly epiphany - only a decade in real time, although it feels longer here - is confused by a halfway-point of sentimental portraits, the only notables being of himself and his mother.

Of course, it's possible to read all sorts of body trauma and emotional angst into the work, but relax your concentration and it just as easily slips back into pastiche again. He did provide a bridge for abstract expressionists such as Willem de Kooning and Jackson Pollock, mainly in his nascent use of an all-over composition, but he never allowed himself to reach such heights. Gorky will remain eternally on the cusp, or on the turn, an amorphous nearly-man as changeable as those he left on canvas.