In 1941, the RCMP recruited Frank Hadesbeck, a Spanish Civil War veteran, as a paid informant to infiltrate the Communist Party. For decades, he informed not only upon communists, but also upon hundreds of other people who held progressive views. Hadesbeck's "Watch Out" lists on behalf of the Security Service included labour activists, medical doctors, lawyers, university professors and students, journalists, Indigenous and progressive farm leaders, members of the clergy, and anyone involved in the peace and human rights movements. Defying every warning given to him by his handlers, Hadesbeck kept secret notes. Using these notes, author Dennis Gruending recounts how the RCMP spied upon thousands of Canadians. Hadesbeck's life and career are in the past, but RCMP surveillance continues in new guises. As Canada's petroleum industry doubles down on its extraction plans in the oil sands and elsewhere, the RCMP and other state agencies provide support, routinely branding Indigenous land defenders and their allies in the environmental movement as potential terrorists. They share information and tactics with petroleum industry "stakeholders" in what has been described as a "surveillance web" intended to suppress dissent. A Communist for the RCMP provides an inside account of Hadesbeck's career and illustrates how the RCMP uses surveillance of activists to enforce the status quo.