In a country that only tolerates dissent in small doses ¡ª and relies on property as its economic growth engine ¡ª a mortgage boycott by hundreds of thousands of middle-class Chinese has become a five-alarm fire for authorities.

It began with a 590-word letter penned by angry purchasers of the half-built Dynasty Mansion project in Jingdezhen, Jiangxi province, whose pleas for China Evergrande Group to complete homes they¡¯d long been paying for had fallen on deaf ears. ¡°All homebuyers with outstanding mortgage loans will stop paying,¡± unless construction resumes before Oct. 20, they threatened.

The ultimatum raced across social media platforms WeChat and Douyin, becoming a call to action for those caught out by China¡¯s rapidly deflating property bubble. Within days, the letter became a template for protests from Shanghai to Beijing, and Shenzhen to Zhengzhou, with homeowners cutting and pasting from it to draft their own boycott manifestos.