They are the perfect weapon
Mandy slaves away at two jobs struggling to support her family while dreaming about resurrecting her father's martial arts academy, a once famous school now forgotten since an accident took his leg. When Mandy rescues wealthy businessman Ho Kwan from muggers he offers her a job as his bodyguard, and she agrees when he also offers to support her family and restore her father's academy. Before long, kidnappers appear and despite Mandy's efforts Ho Kwan is abducted, but not before he slips Mandy a box. Upon investigating, Mandy learns Ho Kwan was kidnapped by ruthless gambling impresario Sung. The box contains a key to a mainframe that controls online betting on fights to the death, and in order to reach Ho Kwan, Mandy will have to join the tournament and gamble with her life.