the money and starts the investigation. He identifies the woman as Sum, a frequent mahjong player. Tam starts tracking her whereabouts through her mahjong playmates, but he is shocked to find each of them
murdered every time he is about to get in touch with them. He discovers a half-burned
photo at one of the
murder scenes. Tam decides that he has to protect the next target of the invisible
murderer. The
photo is the only clue for Tam to uncover the case.
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