He prowls night-time New York in search of the iconic image of the city's dark side that could make him a household name.A chance encounter on a subway station platform with a well dressed, but hard-faced, man sparks an obsession in Kaufmann. He pursues the man, believing him responsible for series of disappearances from late night trains. His paranoia about the man is well founded. Mahogany (the well-dressed man) commits the most brutal of acts on the subway, beating his victims to death and then butchering them.Ex-soccer player Vinnie Jones is perfect as Mahogany. He has the perfect look for a deranged serial killer. But it's the focus on Kaufmann (Bradley Cooper) that makes the film work. Cooper plays the progression from career-desperation into obsession about the subway killer wonderfully.This is a film for the Saw fan, rather than the fan of psychological scares or Freddy-style to…