VENICE (AFP) - Murder, revenge and a quest for justice drive Chinese director Shangjun Cais movie, People Mountain, People Sea, as the surprise film in competition for the Golden Lion award in Venice. Based on a true story, the film sees protagonist Tie set off on a mission to track down his younger brothers killer after the police manage to identify the culprit but let him slip through their fingers. The quest becomes a search for identity and intimacy in a world of brutality and betrayal as Tie hunts for the killer through the underworld of Southwest Chinas Chongqing city and in the hellish bowels of a mine. The films title comes from a proverb describing a gigantic crowd of people according to the director, whose debut movie, The Red Awn, won the 2007 Fipresci prize at the 12th Pusan international film festival.