Acclaimed Hong Kong filmmaker Johnnie To serves as producer in the PTU spin-off Tactical Unit series, giving Andy Ng Yiu Kuen (The Untold Story 2) full rein to directing the latest chapter Human Nature, the third spin-off film of the Police drama P.T.U. This time, yet another Johnnie To regular actor Lam Ka Tung comes in providing reinforcement to the core cast of Simon Yam, Maggie Shiu, and Lam Suet, who return in their law enforcer roles having to make some morally ambiguous decisions.
Tactical Unit officers Sam (Simon Yam) and May (Maggie Shiu) encounter four Mainland robbers on duty one day, but the robbers escape in the ensuing shootout. Meanwhile, in order to evade the loan sharks, heavy-gambling police officer Fat Tong (Lam Suet) hides in a rented room, where he meets and befriends other tenants of the flat – who are none other than the quartet of Mainland robbers. Not knowing Tong’s identity, the criminals invite him to join in their next heist…