Jackie Chan plays a honest, self-effacing cop Chan Ka-Kui assigned to protect Salina, whose key testimony could bring down drug baron Chu. However, the witness manages to get away from Ka-Kui. With no evidence against him, Chu is set free. Chu goes on a vendetta to frame Ka-Kui for a murder. Ka-Kui goes on the run and, with time running out, must quickly find and save Salina from being killed, as well as prove his own innocence.