《独生子女》的故事围绕着英国伦敦的一名大学生梅展开。由于中共的独生子女政策,作为一个女孩,影片的主人翁梅自小被父母遗弃,她被一对友善的英国中产积阶级领养,在英国乡村长大。一天她突然从社交媒体上收到一封来自广州的信,信的作者自称是梅从来不知情的弟弟,并表示他无罪却将被处决,向梅求援。The journey of Mei a Chinese-born young woman as she is called back to Guangzhou by her birth mother in desperately seeking help to save her son who has been wrongly-accused of murder. The journey explores Mei's inner battle as she decides how far she will go to help the woman who gave her away and the brother she's never met.