Red Nights

Red Nights ("Les Nuits rouges du Bourreau de Jade") is a 2010 French-Hong Kong film by Julien Carbon and Laurent Courtiaud. It is a thriller and a tale of erotic horror. The filmmakers call it a Hong Kong "giallo" with mystery, (sadistic) murders, fetishism and women. The film played at the 2010 Toronto International Film Festival in the Midnight Madness section.
Plot.
There is a legend of an executioner who created a poison which brought death through absolute pleasure. This legend repeats nowadays when a French woman flees to Hong Kong after killing her lover and stealing from him an old artifact containing this poison. She meets a mobster from Taiwan and an epicurean and sadistic woman killer, who all want to get the precious poison.