During the Japanese invasion of China, medical students Sun Yang (Chang Yang) and Xu Ruomei (Bai Luming) pretend to be a doctor and his wife to engage in intelligence work behind enemy lines.
| Actor | Role |
|---|---|
 Chang YangSun Yang | Sun Yang |
 Christine Pai Lu-MingXu Ruomei | Xu Ruomei |
 Maria Ye KwongLi Huiru | Li Huiru |
 Chang Mei-YaoMa Ching | Ma Ching |
 Tin ChingGao Jie | Gao Jie |
 Wu Chia-HsiangKawamura | Kawamura |
 Tang TiHung Shih-chi | Hung Shih-chi |
 Lui TatNot listed | Not listed |
 Roy ChiaoNot listed | Not listed |
 Ma ChiNot listed | Not listed |
 Lily Mo ChouNot listed | Not listed |
 Wong HoBig Brother Chen | Big Brother Chen |
 Hung YeungZhang Biao | Zhang Biao |
 Lo WeiNie Yuting | Nie Yuting |
 Law PanNot listed | Not listed |