High school friends Joo-yeon, So-jin, Hyeon-mi and Seon-hee have been close since they were young bu江是香港皇家警察（chá）飛虎隊中最優秀的隊員，卻（què）因某次行動中眼見人質被殺，隊友受傷，遂引疚辭職，江失意之餘，幸得心理女醫師開導，二人遂為好友女（nǚ）探員敏被派協助江，調（diào）查診所張醫師替女病人診病後暴斃，隨後女病人失（shī）蹤一杯紅酒入了喉