Mainland: This study investigates the intermedia agenda-setting (IAS) relationships among major newspapers in Hong Kong, the U.S. and mainland China concerning the 2019 anti-extradition bill protests. It builds on the protest paradigm to characterize the news attributes adopted by leading media outlets and examined the transfer of attribute agendas at both regional and international levels. A total of 9,646 news items were content analyzed. Granger causality tests revealed that mainland Chinese media were the primary agenda-setter among the three, contrary to previous findings that media agendas mostly flow from the U.S. to other countries. Hong Kong newspapers exerted a bottom-up influence on their U.S. counterparts, setting the attribute agenda regarding Chinese authority and international society. A breakdown of the Hong Kong press into three political camps showed diverse IAS relationships. The findings testify to the co-existence of dominant flows and contra-flows in regional and international news flows and imply that organizational and socio-cultural factors can potentially influence IAS.