Whenaseriesofpackagebombsshowuponthedoorstepsofprominentpoliticiansandbusinessmeninthesummerof1919, U.S.BureauofInvestigationAgentWilliamFlynn(Strathairn)isassignedthetaskoffindingthoseresponsible.Hebecomesimmersedinaninvestigationthatuncoversananarchistplottodestroydemocracy.