上海法租界
In 1931 Cai returned to Shanghai to support the Guangdong provincial People's Committee. He then went to Hong Kong to direct party work there. He was betrayed by Gu Shunzhang when attending a meeting in Hong Kong. He was arrested in British Hong Kong and extradited to the Chinese authorities in Guangzhou, which was controlled by the warlord Chen Jitang. He was tortured and executed in August 1931, aged 36. The wife of Cai, Xiang Jingyu, was arrested a few years earlier in the Shanghai French Concession in Wuhan on 20 March 1928 due to the betrayal of members of her group to the police. The French officials turned her over to the Guomindang in April 1928. On the first of May of the same year, Xiang Jingyu was executed by Guomindang police.