I couldn’t choose between the Duck Mascot Fu or the Cheap Spiderman Costume Fu. Fortunately, I didn’t have to. “Detective Chinatown 2,” directed by Sicheng Chen, picks up where the hit original “Detective Chinatown” left off. Once more, we’re watching Haoran Liu as Qin, the intense, shy, and soft-spoken detective mastermind with a photographic memory and an encyclopedic knowledge of the world around him. He can run any riddle, puzzle, code, or cipher to the ground in seconds.