Prequel focuses on xenophobia in turn-of-the-century San Francisco with surprising wit and silliness

This prequel to the huge-grossing Detective Chinatown franchise, though focused on anti-Chinese xenophobia in turn-of-the-century San Francisco, manages to be a rare example of a Sino-blockbuster not filled with maudlin patriotism; it mostly carries its cultural message charmingly and with plenty of self-deprecating humour. At one point, an imperial Chinese investigator toughs it out in order to form an alliance with a gaggle of Irish hoodlums straight from Gangs of New York. “You held yourself so well back there,” his underlings congratulate him, before their leader’s legs give out. “Don’t let the Americans see. I’m about to pee myself!”

The story here is that malevolent forces are stirring the great American melting pot. The son of local Tong leader Bai Xuanling (Chow Yun-fat, still with charisma on tap) is arrested for the murder of the daughter of racist Republican congressman Grant (John Cusack), so the former sends for wunderkind sleuth Qin Fu (Haoran Liu) – apparently deputised by the actual Sherlock Holmes – to get his kid off the hook. Also killed the same night was a Native American elder, whose son Gui (Baoquiang Wang) swears revenge and becomes pig-tailed Watson to Fu’s junior Holmes. No explanation (at first) for why he can speak fluent Hebei dialect.